Elise Huillery
email: elise.huillery@sciencespo.fr

Juliette Seban
email: seban.juliette@gmail.com

Nicolas De Borman

Damien De Walque

Gyuri Fritsche

Emeric Henry

Paul Jacob Robyn

Hadia Samaha

Christel Vermeesch

Emmanuelle Auriol

Roland Ben- Abou

Denis Cogneau

Marc Gurgand

Alice Mésnard

Pieter Serneels

Philippe De

Performance-Based Financing, Motivation and Final Output in the Health Sector: Experimental Evidence from the Democratic Republic of Congo *

Keywords: JEL Codes: H52, 015, I21, I28 1 Introduction

Performance-based nancing becomes a common strategy to improve health sector quality. The ndings of this paper imply that performance-based nancing should take motivational eects and levels of provider capacity into account. Using a eld experiment in the Democratic Republic of Congo, we nd that nancial incentives led to more eort from health workers on rewarded activities, without deterring eort on non-rewarded activities. We also nd a shift from intrinsic to extrinsic motivation. Finally, the increased eort by health workers proved unsuccessful and led to a reduction in revenue, suggesting that health workers lacked the capacity to develop appropriate strategies to perform.

a performance-based mechanism as a way to allocate public resources in the health sector. Second, since performance plays a central and sensitive role in this type of intervention, the study elaborates on measures of performance that are impervious to gaming. Finally, it provides a comprehensive view on the eects of PBF, including its motivational and substitution eects in addition to the eect on performances, which is a novelty in the empirical literature on PBF in developing countries.

Until 2011, the studies of the impact of PBF did not use credible comparison groups: they compare very small groups (generally 2-3 districts) which were not randomly assigned to the dierent treatments [START_REF] Soeters Robert | Performance Based Health Financing Experiment Improves Care in a Failed State.Performance-Based Financing Experiment Improved Health Care In The Democratic Republic Of Congo Health[END_REF][START_REF] Rusa | Performance-based nancing for better quality of services in Rwandan health centres: 3-year experience[END_REF][START_REF] Soeters | Comparison of two output based schemes in Butare and Cyangugu provinces with two control provinces in Rwanda , rapport pour le GPOBA[END_REF]Eicher et al., 2007;[START_REF] Soeters | Improving government health services through contract management: a case from Cambodia , Health Policy and Planning[END_REF][START_REF] Forsberg | Financial incentives in health care. The impact of performance-based reimbursement[END_REF], or the situation before and after the introduction of PBF [START_REF] Sondorp | Afghanistan: Paying NGOs for performance[END_REF]Eicher et al., 2007;[START_REF] Meessen | Output-based payment to boost sta productivity in public health centres: contracting in Kabutare district[END_REF]. The vast majority of the papers advocate that PBF improves accountability, eciency, quality and quantity of service delivery (see [START_REF] Loevinsohn | Buying results? Contracting for health service delivery in developing countries[END_REF] and [START_REF] Eichler | Performance Incentives for Global Health: Potential and Pitfalls[END_REF] for an overview). However, the interference of confounding factors and the fact that is often not possible to isolate the eects of nancial incentives from other elements 3 make the question of the impact of PBF largely unanswered [START_REF] Christianson | Lessons from Evaluations of Purchaser Pay-for-Performance Programs: A Review of the Evidence[END_REF], [START_REF] Eldridge | Performance-based payment:some reections on the discourse evidence and unanswered questions[END_REF], [START_REF] Oxman | Can paying for results help to achieve the Millennium Development Goals? A critical review of selected evaluations of resultsbased nancing[END_REF]). [START_REF] Olken | Should aid reward performance? Evidence from a eld experiment on health and education in Indonesia[END_REF] reports on an experiment using a PBF mechanism to improve the ecacy of a grant program to village committees in Indonesia. Since the PBF mechanism was applied to village committees rather than health workers, this program tests how incentivized village committee members could monitor health workers rather than the direct eect of incentive on health worker behavior 4 . [START_REF] Basinga | Effect on Maternal and Child Health Services in Rwanda of Payment to Primary Health-Care Providers for Performance: an Impact Evaluation[END_REF] conducted a quasi-experimental study on the eect of PBF on use and quality of health services that is the closest to our study. The study took place in Rwanda and combines randomization and a dierence-in-dierence strategy in order to control for potential selection eects 5 . It nds that PBF is an ecient way to increase health service utilization of some of the targeted services and targeted health outcomes [START_REF] Basinga | Effect on Maternal and Child Health Services in Rwanda of Payment to Primary Health-Care Providers for Performance: an Impact Evaluation[END_REF], De Walque et al. ( 2013)), as well as worker productivity [START_REF] Gertler | Using Performance Incentives to Improve Medical Care Productivity and Health Outcomes[END_REF]. However, the study does not inform about the eects of PBF on the provision of non-targeted services (substitution eect), and it does not provide direct evidence on motivational eects. To conclude, the literature on the eect of PBF on health outcomes is still limited due to the small number of studies providing clean identication of the impact of the incentive, and due to the lack of evidence on motivational and substitution eects in developing countries 6 [START_REF] Miller | Pay-For-Performance Incentives in Low and Middle-Income Country Health Programs[END_REF]. This paper presents the ndings of a research project conducted in the Haut-Katanga district of the Democratic Republic of Congo (DRC) between 2009 and 2013 to study the eect of a PBF approach compared to a xed payment approach. The 96 health areas present in the Haut-Katanga district were randomly assigned to performance-based or xed payments, while ensuring that the same amount of governmental resources was allocated to each group to neutralize the ressource eect. In this study, the PBF mechanism was based on a point system where the number of points was determined by the number of patients for 7 services (plus 3 additional services for referral facilities), relative to all PBF-group facilities. The two mechanisms have been in place from June 2010 to September 2012. Administrative data was collected throughout the project, spotchecks of health workers' attendance were performed in July, August and September 2012, and a nal independent survey was administered from December 2012 to Feburary 2013 -after the incentives have been withdrawn. The objective of this research was to provide evidence on the eects of the performance-based payment on (i) the supply of and prices of health services, (ii) health workers' work-related stress and motivation, (iii) service utilization, and (iv) the population health status. The analysis distinguishes targeted and non-targeted services in order to check for the potential substitution eect of incentives. It is important to note that there are many dierent PBF approaches (see Miller and Barbiaz (2013) for a review). In this study, the design of the performance-based strategy was kept simple so that it could be feasibly implemented in the dicult conditions of DRC. Consequently, the strategy lacked some of the more technically complex attributes that might be seen in other PBF interventions, especially stringent quality measures tied to performance payments. The payment was only conditional on the number of patients for some pre-determined services. The results should thus be considered as specic to this particular PBF approach, although we refer to it in the rest of the paper as PBF for simplicity.

This study nds that the introduction of the nancial incentives in the treatment group led to concrete changes in health workers behaviors. Health workers made more eort to attract patients: [START_REF] Ariely | Large Stakes and Big Mistakes[END_REF] they were found to be present at facilities more often; (2) fees for targeted services were signicantly reduced; (3) the health workers organized more preventive health sessions at facilities; (4) the health workers conducted more community-based outreach activities to sensitize the population about the services oered by the facility. Overall, the nancial incentives induced an intensication of eort to increase utilization of targeted health services. Equally important, the evaluation found that the increased eort invested in the targeted services did not happen at the expense of the eort invested in the non-targeted services: there were no substitution of non-rewarded activities for rewarded ones. Also, although the reward was contingent on service volumes, it did not have a negative eect on service quality (which did not increase neither).

Surprisingly, the increased eort did not led to any change in utilization of health services by the population, which echoes the argument by [START_REF] Glucksberg | The inuence of strength of drive on functional xedness and perceptual recognition[END_REF] or [START_REF] Ariely | Large Stakes and Big Mistakes[END_REF] that increased motivation may not lead to increased performance. It is crucial to think about the barriers that impede the increase in utilization of health services and were not addressed in the strategies implemented by the incentivized health workers, such as the lack of awareness about the benet of health care services, or the general dissatisfaction with the quality of care. This result suggests that health workers did not develop innovative actions able to stimulate the demand for health services, which is arguably not an easy task in a context where people are generally low educated and uninformed about modern medicine. As facilities in the treatment group reduced the prices of their services more than comparison facilities without attracting more patients, there was less total revenue in these facilities (42% less), even though the two groups received the same subsidy payment level from the government. Consequently, the nancial incentive payment mechanism resulted in a 34% reduction in sta revenues, and in a reduction in health worker job satisfaction. The lower levels of job satisfaction might be due to the fact that an increase in eort led to a reduction in income, or to the exposure to the incentive itself. Our study cannot disentangle between these two explanations.

Finally, an important result is that sta attendance, which was found higher in the incentivized health facilities than in the comparison facilities when the incentives were in place, was found lower few months after the incentives were withdrawn. Also, the previously incentivized health workers were found to attach more importance on job material benets relatively to non-material benets than non-incentivized health workers. We show that these eects are not attributable to the decrease in worker income, suggesting that incentive-based payments deterred some of sta intrinsic motivation.

There are key policy implications of our ndings for governments considering PBF as a way to allocate public ressources to the health sector. First, PBF increases health worker overall motivation without deterring service quality or non-rewarded services, meaning that health workers are strategic but not cynical so that they would swap non-rewarded actions for rewarded ones. However, two types of precaution should be considered. First, contingent rewards might reduce the intrinsic component of health worker motivation so incentives should be used as a permanent instrument otherwise it would backre. Second, our results suggest that contingent rewards might not be appropriate when the task is dicult and requires sophisticated strategies, because incentivized agents provided more-of-the-same eort but did not develop novel ideas to reach complicated goals.

The translation of motivation into performance may thus be better in contexts where the rewarded task is easy.

The remainder of the paper is organized as follows. Section 2 discusses the theoretical background. Section 3 presents the context in which the experiment was set up and the experimental design. Section 4 examines the data and econometric approach. Section 5 presents the eects of PBF compared to a xed payment approach, and Section 6 concludes.

Theoretical Background

In this section, we consider a simple framework that provides some structure to the ndings in the literature that extrinsic rewards may backre [START_REF] Glucksberg | The inuence of strength of drive on functional xedness and perceptual recognition[END_REF], Deci (1971), [START_REF] Lepper | Undermining Children's Interest with Extrinsic Rewards: A Test of the Overjustication Hypothesis[END_REF], [START_REF] Deci | Intrinsic Motivation and Self-Determination in Human Behavior[END_REF], [START_REF] Kohn | Punished by Rewards[END_REF], [START_REF] Ariely | Large Stakes and Big Mistakes[END_REF], among others). The motivation for this section is to show that reasonable assumptions on workers' behavior, dierent from informational and reputational eects, are able to produce predictions consistent with the evidence found in the literature.

Let's consider that an agent engages into a certain task if and only if her interest in the activity is larger than the cost of undertaking the activity c. If the agent succeeds in producing the output, her benet in the activity is two-fold: the intrinsic value that the agent attributes to the output, V , and a contingent reward b. If she does not succeeds the benet is zero, and the probability that she succeeds if she undertakes the activity is her ability θ. Her utility of engaging into the activity is thus given by U = θ(V + b) -c. Holding everything else equal, the reward b therefore increases the probability that the agent engages into the activity. [START_REF] Benabou | Intrinsic and Extrinsic Motivation[END_REF]'s framework provides an explanation of why rewards may be counterproductive during the period when incentives are in place in presence of information assymmetries: rewards from a knowledgeable principal may inform a more ignorant agent about the diculty of the task c, or about her ability to succeed in the task θ, or even about the intrinsic value of the task V 7 . These informational eects of rewards have a negative impact on agent utility which might be large enough to oset the positive impact of θb. Moreover, the permanent nature of informational eect makes the eect on motivation also permanent after incentives have been withdrawn. Benabou and Tirole (2006) adds another explanation of why extrinsic rewards might crowd out agent's eort during the period when incentives are in place due to the idea that an agent concerned by social reputation or self-respect concerns might want to reduce her eort in response to the introduction of extrinsic rewards in order to signal her intrinsic motives. As [START_REF] Gneezy | When and Why Incentives (Don't) Work to Modify Behavior[END_REF] summarizes, economists think about the eects of incentives on behavior in terms of information and signaling.

However, the literature suggests that informational and reputational eects are unlikely to drive all situations where rewards backre. For instance in Deci (1971), Zeevi (1971) or [START_REF] Lepper | Undermining Children's Interest with Extrinsic Rewards: A Test of the Overjustication Hypothesis[END_REF], students who are oered external rewards for performing at some tasks like solving a serie of puzzles or art activity are less likely to engage into these tasks after the external reward has been withdrawn. The authors do not nd evidence that they feel less able to perform or nd the task more dicult, but they nd that students express less interest in the task itelf. The explanation through information asymmetries does not t well with these observations because it sounds unlikely that the students learned much about the diculty of the puzzles, or their ability to perform the puzzles, or the intrinsic value of solving puzzles. In such contexts where information assymmetries seem small or non-existent, the decrease in motivation after the reward was withdrawn should be found somewhere else. In fact, the authors point to the fact that the introduction of extrinsic motives causes a shift in attention from the value that the agent attributes to the output V in favor of the external benet b. Actions perceived as ends in the absence of external motives tend to become means when external rewards are introduced (Lepper et al. 1982). [START_REF] Deci | Intrinsic Motivation and Self-Determination in Human Behavior[END_REF] argues that rewards change the locus of control from internal to external and make agents bored, alienated and reactive rather than proactive. [START_REF] Kohn | Punished by Rewards[END_REF] notes that rewards make people less enthousiatic about their behaviour. Overall, what psychologists term the overjustication eect is compatible 7 Individuals may have imperfect memory why they engaged in the task. Note that in this case there is no need for the principal to have information that the agent does not have. It is just information that the agent had and lost.

with situations where principals and agents have similar information about agent's ability or the diculty and intrinsic value of the task to start with, but agents pay less attention to the intrinsic value of the task after they were oered extrinsic rewards.

We thus propose (and test in our empirical analysis) an alternative habit-forming based theory of motivation by introducing a parameter α reecting the attention paid to the extrinsic benet from the task b, and a parameter β reecting the attention paid to its intrinsic value V . Total motivation is given by: U = θ((βV + αb) -c where α and β reect weights attached to extrinsic versus intrinsic motives in agent's utility. Our framework is based on two key assumptions: (1) First, β = f (α) with f (.) ≤ 0, which stands for the idea that people have limited attention in the sense that more attention paid on extrinsic motives can only decrease attention paid on intrinsic ones, or do nothing. (2) Second, attention is prone to habit-forming: as soon as attention is drawn on a motive, it remains permanently because people don't forget. For example, an awareness campaign that would draw agent's attention to the intrinsic value of the task would shift β from 0 to a positive value. Similarly, the introduction of a nancial remuneration for succeeding at the task would shift α from 0 to a positive value. Then the levels of V and b are likely to vary over time depending on new information, experience, principal's decisions etc., but agent's attention paid on intrinsic and extrinsic motives cannot disappear. Attention parameters α and β evolve over time only through the relationship β = f (α) in contexts where attention is limited (f non constant).

Under this framework, post-reward motivation is smaller than pre-reward one if and only if f < 0. The mechanism is as follows:

Before Exposure to Extrinsic Rewards The agent has never received any extrinsic reward for engaging into the task (b = 0), and therefore she does not pay attention to extrinsic motives (α = 0). The utility of engaging into the activity is

U 0 = θf (0)V -c.
During Exposure to Extrinsic Rewards The principal introduces an extrinsic reward b > 0, and the agent pays a level of attention α > 0 to the reward. The utility of engaging into the activity

is now U 1 = θ(f (α)V + αb) -c. Since α > 0, f (α) < f (0)
and U 1 can be both smaller or larger than U 0 depending on the size of the increase in motivation due to the new extrinsic reward αb relative to the loss in motivation due to the shift of attention paid on intrinsic motives (f (0) -f (α))V .

Typically small rewards in contexts where intrinsic motives are large would decrease the total motivation, while large rewards in contexts where intrinsic motives are small would increase the total motivation.

After Exposure to Extrinsic Rewards The principal stops providing the agent with rewards (b is back to 0). However, attention parameters remain the same because attention is prone to habit-forming, and the utility of engaging into the activity is now: U 2 = θf (α)V -c. U 2 is smaller than U 1 if and only if α > 0, meaning exposure to extrinsic reward in the previous period eectively drew agent's attention on extrinsic motives. Moreover, U 2 is smaller than U 0 if and only if f < 0, meaning agent's attention is limited.

In a context of unlimited attention (f ≡ 0), the introduction of an extrinsic reward would attract some new attention from the agent without decreasing pre-existing attention paid to the intrinsic value of the task V . After the extrinsic reward is withdrawn, pre-existing attention paid to V would remain intact and motivation would be back at its pre-reward level, without any detrimental eect on later motivation.

In the empirical part of the paper, we test this theoretical framework by eliciting the relative size of α and β and comparing agents who have been exposed to extrinsic reward (the performancebased nancing system) and people who have not. A testable prediction is that α should be larger and β smaller among the former than the latter. We also provide evidence on the comparison between U 0 , U 1 and U 2 .

Finally, rewards may backre not because of reduced motivation, but because increased motivation is accompanied by reduced performance. There are two main explanations for the reduced performance. One is the multitask interpretation proposed in Hölmstrom and Milgrom (1991) where agents focus on the rewarded actions at the expense of other actions that might be necessary complement to perform well, which we refer to as a substitution eect 8 . Second, [START_REF] Glucksberg | The inuence of strength of drive on functional xedness and perceptual recognition[END_REF] and [START_REF] Ariely | Large Stakes and Big Mistakes[END_REF] observe that people who are oered a reward for performing at some tasks perform better at simple tasks but worse at tasks calling for -even rudimentary-cognitive skills, indicating that rewards generate negative stress limiting one's creative thinking [START_REF] Baumeister | Choking Under Pressure: Self-Consciousness and Paradoxical Eects of Incentives on Skillful Performance[END_REF].

In this case, lower ability is associated with larger rewards (θ (b) < 0) not because the agent infers that his ability is lower than expected, but because larger rewards constitutes larger stakes and larger stress which narrows the mind and reduce ability to perform [START_REF] Kamenica | Behavioral Economics and Psychology of Incentives[END_REF]. McGraw and McCullers (1979) explains that reward leads to underachievement when the task requires open-minded thinking because the focus of attention limits one's capacity to draw unusual connections between elements. Under negative stress, the agent initially provides more eort and yet produces a smaller output 9 . In other words, U is larger but a change in the content of the eort makes it less productive. One example would be a student whose motivation in passing her exam gets larger due to the promise of a gift conditional on passing, who would spend hours and hours reading her lessons without being able to learn because her mind would be distracted. In the context of health workers exposed to nancial rewards, the phenomena may show itself through motivated but stressed out workers who would be more tense, less staid with patients, or would decrease time spent with the patients in order to consult more of them, etc.

All in all, the theory leaves thus room for both positive and negative eects of nancial incentives on both workers' eort and performance, making the question empirical in essence.

3 Experimental Set-Up

Background on Health in DRC and Haut-Katanga

The Democratic Republic of Congo (DRC) is the second largest country in Africa by area, with the fourth largest population at 66 million (World Bank, 2012). It is also among the poorest countries in the world: the country is ranked second from the bottom of the Human Development Index (186 out of 187 in 2012) (UNDP, 2012), with an estimated per capita income of US$ 220 (current) in 2012 (World Bank, 2012). Impoverished by decades of war, instability and bad governance, it is not surprising that DRC is not on track to reach the health-related MDGs. Since the democratic elections in 2006, the country has started a slow reconstruction phase and a decentralization process, with the election of provincial governments, including provincial ministers of health. Developing and putting in place eective service delivery models such as Performance-based Financing (PBF) is be a strategy for improving health outcomes among the population.

The district of Haut-Katanga entails 1.26 million people in the province of Katanga in the south-eastern corner of the DRC. From September to November 2009, a survey was conducted in order to better understand the health situation in Haut-Katanga by providing a description of the functioning of the health facilities as well as the characteristics and behavior of the health workers, patients and households in the region. The survey sample entailed 152 health facilities (5% referral centers, 71% health centers and 24% health posts) 10 . Descriptive statistics from this survey can be viewed in Appendix Table 4. This survey indicated that the initial situation of the health facilities in Haut-Katanga was worrying not primarily because of the coverage for basic health services but rather because of the poor quality of health services. Indeed, as for coverage for health services, the ratio of health workers to total population was quite good with 1 health worker for every 1860 individuals 11 , meaning that stang was not the main issue in Haut-Katanga. Accessibility of health facilities was also pretty good: 87% patients live at 10km or less and 70% spent less than an hour to come to the facility.

However, the poor quality of infrastructure was striking: only one out of four facilities had access to a water tap, the same for electricity. The majority had only low-cost basic equipment. One health worker out of four did not receive any xed wage from the health facility. As a consequence, the typical health worker earned 61% of his income from the health facility, while 39% from other jobs and/or agricultural production. However, health workers spent 52 hours per week working in the health facility. They received 35 patients the week before the survey, which means that each health worker received about 7 patients per working day, so health workers were not overworked and should spend some time waiting for patients to come. Patients reported quite short consultation time (16 minutes on average), and twice as much waiting time before the consultation (30 minutes on average) 12 . 56% of patients had to pay a fee for the service, although the median fee for a visit was quite low 800FC (0.88$).

In this survey, the health status of the population was found preoccupying: 25% of the sample had been sick in the last four weeks, with malaria and diarrhea being the most prevalent diseases.

Concerning maternal health, 31% of births in the last 12 months were not attended in a formal health facility. Mothers utilized more prenatal than postnatal health services: 76% of women pregnant in the last 12 months had at least one prenatal visit while only 10% attended a postnatal visit. However, only a third of prenatal visits included the minimum tests, according to women's recall. Despite frequent immunization campaigns, only 13% of children under 5 years-old were able to present an immunization card (although based on mother's declaration a majority of children got immunized at least once). Finally, we found low exposure to prevention campaigns other than immunization, with around two thirds of the households never exposed to any HIV prevention, 10 161 health facilities were recognized as part of the government health system in the district, among which 5 hospitals were excluded from the study and 4 health centers could not be reached.

11 The ministry of health considers that there should be at least one health worker for every 1500 individuals. 12 This survey did not allow for assessing the technical quality of medical procedure. child nutrition, or maternal health campaign.

Experimental Design Payment Calculation

In Haut-Katanga district, the 96 health areas (totalizing 152 health facilities) were randomly assigned to one of two payment systems. In the xed payment group, the amount allocated to each facility was calculated based on the sta in the facility: a list of eligible workers was established at the beginning of the pilot by the Ministry of Health. Each worker was entitled to a given amount of governmental payment depending on his/her grade and experience. In contrast, payments to the PBF health facilities were to be made after verication of declared service volumes by facilities.

The targeted services included seven services at the primary care level (outpatient rst curative consultations, prenatal consultations, deliveries, obstetric referral, children completely vaccinated, tetanus toxoid vaccination, and family planning consultations) and three additional services at the secondary care level (C-section, blood transfusion, and obstetric referrals to hospitals). Relative prices for each service are presented in Appendix Table 1.

Formally, payments to health facilities can be written as:

P i,m = α i + β m Q i,m
where P i,m is the payment to facility i in month m, α i represents a xed component, Q i,m is the vector of targeted service quantities provided by facility i in month m, and β m is the vector of prices that the government attach to each targeted service in month m. The PBF group was characterized by a pure performance-based mechanism (α i = 0 and β m > 0), whereas the comparison payment group had a pure xed payment (α i > 0 and β m = 0). In order to ensure neutrality in the level of nancing between the two groups and isolate the incentive eect from the resource eect, the total budget allocated to health facilities in the PBF group was the same as the total budget allocated to health facilities in the xed payment group: ∀m,

n i=1 α i = n i=1 β m Q i,m
where n is the number of health facilities in the PBF and in the xed-payment group. Hence, noting Q m the average service provision in the PBF group in month m and α the average payment in the xed payment group:

α = β m Q m
Since the budget of the health provincial authorities was xed and could not vary every month depending on the average service provision in the PBF group, α was xed and β m was adjusted accordingly at α Qm 13 . Although relative prices attached to the targeted services were constant, absolute prices and facility payments were thus determined by the quantity of services provided by the facility relative to the quantity of services provided by the other incentivized health facilities.

The budget used in this experiment estimated at $0.43 per capita per year (average monthly facility payments were $550 and the average catchment area population was 12,900) 14 . The average monthly payment by facility from June 2010 and September 2012 does not dier in the xed payment and in the PBF group. This conrms that the experimental design was respected and that the study isolates the incentive eect from any resource eect. Figure 2 shows the distribution of the average monthly facility payment over the study period by treatment status. Payments proved more disperse under PBF than uner xed-payment, suggesting heterogenous responses to the incentive with some health facilities getting less than under a xed payment mechanism and others getting more.

Performance Verication

Service volumes were measured by use of monthly reports submitted by facilities, in which the number of patients for each targeted service was reported. Subsequent verication of declared service volumes was conducted by verication agents through (i) comparing reported volumes with those found in health facility registers 15 , and (ii) verifying that the information noted in the registers was true by conducting community verication: a random sample of 30 patients 16 from registers were selected and visited by independent associations to check the accuracy of the information reported in the facility register 17 . A system of nancial sanctions was integrated in order to reduce 13 The other way to equalize the two total budgets is to x βm = β and adjust α accordingly at βQm. This technique was used in the Rwanda experiment where the governmental budget could increase according to the average service provision in the incentivized group.

14 This is lower than in other contexts where output budgets range between $2 and $3 per capita per year. [START_REF] Eldridge | Performance-based payment:some reections on the discourse evidence and unanswered questions[END_REF] Register verication was also meant to take place in health facilities under the xed payment mechanism since the government wanted to improve the accountability of health facilities in general, not only as an element of PBF.

At endline, the average number of register verications in the last 12 months is 7 in both in the PBF and in the xed-payment group (p-value of the test of equality of means in the two group = 0.48).

16 The 30 patients were chosen such that each targeted service is present in the sample, but none of the non-targeted services.

17 Community verications were meant to take place only in the PBF group as part of the nancing mechanism.

However, we conducted community verications in the xed payment health facilities for impact evaluation purposes

(1 community verication by facility in the comparison group). The xed payment health facilities had no incentive to cheat on service volumes so the comparison of discrepancy rates between the PBF and the xed payment groups providers' incentives to submit fraudulent reports and over-report phantom patients.

In reality, the community verication system proved weak: rst, PBF facilities only received on average 3 community verications throughout the pilot. Second, there was no eective nancial sanction associated with being caught for fraudulent over-reporting. Specically, the reductions in payments were proportionally equal to the percentage of patients not being identied through community verication. For example, if 18% of patients were not found through community verication, the facility would only receive a reduction of 18% in their corresponding payment and no additional sanctions were enforced. Despite the weak verication process, we did not nd any signicant dierence in the propensity to report phantom patients in the registers: the average proportion of missing patients was found 17% in the comparison group whereas 21% in the PBF group, the dierence being not statistically signicant (p-value 0.25). However, the health workers in the PBF group were signicantly more likely to ll out consultation reports for their patients than in the xed payment group: in the endline survey, 94% of health workers declared that they ll out a consultation report for each patient in the PBF group, whereas only 78% of health workers in the comparison group (the dierence is signicant at the 1% level). Since patients are reported in the register based on consultation reports, service utilization is under-reported in the xed-payment group. It is interesting to note that the issue with administrative data is not that incentivized health workers inate artically the number of patients, but rather that the non-incentivized workers under-report the number of patients as they don't have any nancial benet of paying the cost of reporting accurate service volumes. Overall, it is crucial to rely on an independent source of information about service utilization for the impact evaluation since administrative data does not give an accurate idea of service utilization in the xed-payment group.

Autonomy of Payment Allocation

It was found that the autonomy of payment allocation among facility sta in the PBF group led to a more egalitarian distribution of payments among workers. In the xed payment group, 77%

of health workers received a share of the payment, whereas 93% of workers in the PBF group (the dierence is signicant at the 1% level) 18 . Actually, PBF benetted to non-technical workers (pharmacists, managers, secretaries, receptionists and maintenance workers) who are not in the allow for dierentiating cheating from natural -unavoidable-discrepancies due to the fact that some patients moved or were absent at the time of the verication.

18 This information was collected at endline from the facility heads. The facility heads listed the workers in the facility, indicated whether each of them received a share of the last payment, and the corresponding amount.

governmental payroll and therefore do not receive a share of the xed payment 19 . Consistently, the average last payment to health workers showed less dispersion in the PBF group: the standard deviation is 36% lower in the PBF group than in the comparison group (the dierence is signicant at the 5% level), which conrms the nding of a more egalitarian distribution of the payment among workers in the PBF group.

Resulting Structure of Worker Motivation

We want to link our theoretical framework and the actual context of this specic experiment.

The task workers engage into is attracting patients, and the output is the number of patients.

The experiment manipulates the structure of motivation by adding a contingent reward in worker utility of attracting patients. In the xed payment group, worker utility of attracting patients is driven by the intrinsic value they attribute to this task, as well as a contingent benet coming from user fees. In fact, the more health workers consult patients, the higher facility's revenue from user fees, which constitutes a large part of workers' remuneration. Workers in the xed payment group thus already pay attention to extrinsic motives through this benet from user fees. Let's denote (α 0 , f (α 0 )) the levels of attention paid respectively on extrinsic and intrinsic motives, and F the level of worker remuneration from user fees, in the xed payment group. Using the parameters of our theoretical framework, workers' utility of attracting patients in the xed payment group is thus

U 0 = θ(f (α 0 )V + α 0 F ) -c
The dierence with the PBF group is the introduction of a new contingent reward from the government. While governmental payments to the xed-payment facilities are xed and do not play a role in workers' decision to attract patients or not, they do play a role in the PBF group by increasing workers' benet of engaging into this task. Let's denote (α 1 , f (α 1 )) the new levels of attention paid on extrinsic and intrinsic motives resulting from the introduction of this new category of contingent reward, and P the governmental payment. Workers' utility of attracting patients in the PBF group is thus U 1 = θ(f (α 1 )V + α 1 (F + P )) -c. After government payments are withdrawn, worker utility of attracting patients is unchanged in the xed payment group, while

it becomes U 2 = θ((f (α 1 )V + α 1 F ) -c = U 1 -θα 1 P in the PBF group.
In the rest of the paper, we will present evidence on the relative size of U 0 and U 1 , U 0 and U 2 , as well as α 0 and α 1 .

19 Since the xed payment is calculated based on the number and qualication of workers on the governmental payroll, the workers typically receive the amount of money corresponding to their contribution to the xed payment. Administrative Data Administrative data was collected every month from January 2010 to December 2012 from all the 152 health facilities participating in the pilot. This data includes for each month the number of targeted services provided, the payment due to the health facility, the actual payment made to the health facility, whether a performance verication occurred and related indicators (% missing patients and consequent nancial sanctions).

Qualitative Data In April and June 2012, qualitative interviews were performed in 31 health facilities randomly selected in 4 out of the 8 health zones (Kafubu, Kipushi, Kasenga and Lukafu).

In each facility, one interview was done with the facility head and another one with a health worker (on a voluntary basis). In total, 29 facility heads and 31 health workers were interviewed, all by the same person. They were equally distributed between the PBF group and the control group.

Questions were all open and dealt with the perception of the payment (transparency, fairness, understanding of the calculation), the general functioning of the health facility, recent changes that might have occurred, and obstacles to improve the number of patients and the quality of services.

Attendance Spotchecks Unannounced spotchecks were performed in July, August and September 2012 in order to collect data on worker attendance in the health facilities that is impervious to gamming.

Endline Survey

Outcomes of Interest

Accessibility of Health Services -Cost Changes in user fees in the incentivized group would take place as sta understands the economics by which reducing the cost to patients would lead to increased utilization and, therefore, increased payments. The reverse eect may happen on non-targeted services, as a way to compensate for the loss in revenue from targeted services, or discourage demand for non-targeted services. User fees were collected from the facility heads, and also from patients straight out of consultation as well as households who used health services in the last 12 months. In order to compare fees across the largest number of health facilities, we compare user fees for the most commonly oered services: curative consultations, birth delivery, prenatal visits, postnatal visits, and preschool consultations. To improve statistical power to detect eects that go in the same direction within a domain, we also present ndings for a Fee Summary Index 20 In the facilities stang more than 10 health workers, 10 were randomly chosen from the list of all health workers during the facility head interview. The health workers who were present the day when the interviewer visited the health facility were interviewed on-site, whereas the others were visited at home. Only those health workers who were out of the neighborhood at the time of the survey (because they were on vacation or because they temporarily migrated) could not be interviewed. [START_REF] Holmström | Multitask Principal-Agent Analyses: Incentive Contracts, Asset Ownership, and Job Design[END_REF] The selection of the 20 households was done as follows: four axes in the locality were randomly drawn from a central point, then one household was visited every ve houses on each axis. -On two axes, all households were eligible and took the survey if it consented to (otherwise the next household was visited). After each interview, the interviewer went ve houses further and continued the selection until he could interview 5 household on each axis. -On the two other axes, only households where a woman had been pregnant in the last 12 months were eligible. If the household did not meet the criteria, then the next household was visited etc. until an eligible household was found.

After each interview, the interviewer went ve houses further and continued the selection until he could interview 5 household on each axis.

that aggregates information over all these user fees (following Kling et al, 2007), as well as a Fee Summary Index for targeted services (curative and prenatal consultations, and birth delivery) and a Fee Summary Index for non-targeted services (postnatal and preschool consultations).

Accessibility of Health Services -Opening, Attendance, Preventive Sessions and Outreach Activities Information about opening hours was collected from facility heads. Worker attendance (number of health workers present at the facility) and on-the-job eort (number of health workers actually working) was collected from the unannounced spotchecks when the interviewer arrived 22 . The number and qualication of workers, the number of service varieties oered, and the number of preventive sessions organized at the facility in the last 12 months were collected from the facility heads. The number of outreach activities in the community in the last 12 months was collected from the health workers. Finally, patients and household members were asked about waiting time before the consultation, and whether s/he could consult every time s/he visited.

Service Quality Service quality is primarily measured by technical quality. Consultation time is considered as a component of service technical quality, although we use compliance with standard medical procedures as the main indicator. Compliance was assessed on all patients straight out of consultation who were asked whether the three following procedures were applied during the consultation: being weighted, examined and having his tension checked. Compliance was also assessed on women who gave birth in the last 12 months who were asked about standard procedures applied during prenatal visits (weighing, stomach palpation, tension check, stomach measure, HIV test, tetanus shot, blood test, urine analysis and information on immunization schedule) and postnatal visits (stomach palpation, child weighing, child examination, child immunization and child immunization card). We also measure the proportion of patients straight out of consultation who were prescribed drugs without them being examined and the number of days women stay at the facility after giving birth. Beside, we use the proportion of patients who understand the diagnosis and prescriptions, as well as the proportion of patients and household members who are satised with the visit, as complementary measures of service quality.

22 Note that the interviewer reported the number of workers present and working without telling to the facility heads and the workers. The purpose of the visit was ocially related to administrative matters and not attendance checks in order to avoid any interference with worker behavior at a later point. Observational data on workers' attendance and on-the-job eort was anonymous and aggregated at the facility level.

Service Utilization First, we asked women in the households whether they have been sensitized about postnatal and prenatal visits, immunization and family planning by health workers, as well as whether they know the schedule of the corresponding sessions at the facility. This information provides evidence on the immediate eects of the outreach activities performed by the health workers.

Second, we measure utilization of health services during the last 12 months at the household level: the proportion of individuals who visited a health facility, who got sick but did not visit, and -for those who visited-the number of days they waited before they visited. We measure utilization of immunization using the proportion of children aged 0-5 who took at least one immunization shot, the number of immunization shots reported in the immunization card, and the proportion of children who have a scar from TB immunization on the shoulder. Since utilization of maternal health services is also an important public health objective, we use indicators as the proportion of attended deliveries among mothers who gave birth in the last 12 months, the proportion of C-sections, the number of prenatal and postnatal visits at the facility, the proportion of mothers supplemented with iron and taking medication to prevent malaria, and the number of months mothers breastfeed their newborn. As for utilization of family planning, we observe the proportion of women and partners who are in favor of the use of family planning, and the proportion of women actually using family planning (we distinguish traditional and modern methods).

Finally, we use the number of patients in the last month as reported by the facility head (at the facility level), and by the health workers (at the individual level). This information provides evidence on service utilization after PBF was withdrawn in order to assess how the eects of PBF on service utilization evolved compared to the period when PBF was in place.

Population Health Status We use mortality rates and under-5 weight-for-height z-score to measure health status in the population. To assess mortality rates, we use information about the number of persons who died in the last 12 months in the household, and among them the number of women who died for perinatal reasons and the number of children under 5. We also use the proportion of new-born in the last 12 months that are still alive. Finally, we use the standard under-5 weight-for-height z-score as an assessment of child nutrition status.

Health Facility Revenue Depending on the price-elasticity and access-elasticity of the demand for health services in the population, it is unclear what the eect of PBF on total resources in health facilities is. We thus examine all sources of revenue at the facility level the month before the endline survey as reported by the facility head, as well as workers' payment the month before the survey as reported by the facility head and health workers themselves.

The enumerators also observed the quantity and quality of equipment and infrastructure during their visit, which reect both total revenue and management decisions made at the facility level. We constructed three indices, each index being the rst component of a principal component analysis. Health workers' satisfaction, anxiety and motivation At the time of the endline survey, workers are no longer incentivized in the PBF group so the incentive structure does no longer dier between the two groups: workers' behavior is driven by intrinsic motivation (perceived value of the job) and extrinsic motives (job remuneration). Any dierence in worker behavior therefore reects persistent eects of PBF on either intrinsic motivation, or job remuneration. Sta attendance provides a measure of workers' total motivation (intrinsic plus extrinsic). We also elicit health workers' motives. Workers were asked about the main advantage of their occupation, then about the main inconvenient. These questions were open in order to not induce any type of response and capture occupation characteristics that are the more salient to them and naturally come at the top of their mind. We classied the responses into seven categories of advantages: social recognition, remuneration, material comfort, care about others' health and life, power, interest in the activity, and six categories of disadvantages: lack of social recognition, low remuneration, low material comfort, responsability over others' life, too much pressure and responsability, risk of being sick due to the contact with patients. We calculate the proportion of workers who mention either remuneration or material comfort as the main advantage, or low remuneration or low material comfort as the main disadvantage. We use this proportion as a measure of the relative importance of extrinsic versus intrincis motives in workers' total motivation.

Empirical Strategy

Validation of the Experimental Protocol The internal validity of the impact evaluation relies on the comparability of the xed payment and the PBF groups as observed at endline. With a large number of units of randomization, the law of large numbers insures that the characteristics in both groups are balanced. Here randomization was done on 96 health areas and it is preferable to check out whether the pre-program characteristics of the xed payment and the PBF groups are similar.

This comparison was done using the 2009 survey. As explained earlier, only 85% of health facilities involved in the experiment took the 2009 survey. As a result, 129 out of the 152 pilot health facilities can be observedto check how characteristics were initially balanced between the xed payment and the PBF groups.

Most initial characteristics are balanced, although the urban health facilities (17% of the sample)

were not equally distributed in the PBF and xed payment groups: they represent 12% of the PBF health facilities while 23% of the xed payments ones. Since the urban health facilities, sta, patients and households are likely to dier from the rural ones, Appendix Table 4 present the means of some observables collected in 2009 in the PBF and xed payment groups and t-tests for the null hypothesis that the dierence is zero controlling for a dummy indicating whether the unit of observation is located in a urban area. 8 dierences in means are signicant at the 10% level or less out of 78 tests, meaning the exact amount that would be expected with random sampling variations.We are therefore condent that most dierences in outcomes at endline between the two groups are not driven by initial conditions as long as we control for urban location.

Estimation Strategy For each outcome of interest, we show the estimation results of an equation of the form:

Y i = α + βP BF i + X i γ + ε i
Where PBF is a dummy for being in the PBF group. Because the treatment was randomly assigned, it is in expectation uncorrelated with the error term and can therefore be estimated through OLS. Coecient β estimates the average local eect of PBF and is presented in the rst column of our result tables. We show the p-value for a test that this coecient is equal to zero in the second column of the result tables.

The unit of observation i varies: it stands either for a health area, a health facility, a health worker, a patient straight out of consultation or a household. Following the results of the balance checks discussed above, we control for the few variables which proved unbalanced in 2009. The set of characteristics X i varies according to the unit of observation i: At the health area level, it includes a dummy indicating the health zone (the Haut-Katanga province entails eight health zones), a dummy indicating whether the majority of the health facilities in the area are urban, as well as a dummy indicating whether the majority of the health facilities in the area are denominational.

At the health facility level, it includes dummies indicating the health zone, whether the health facility is urban, and whether the health facility is denominational. At the health worker level it also includes dummies indicating that the health worker is a female, a doctor, a nurse, as well as the age and number of years of experience of the health worker. At the patient level it includes a dummy indicating that the patient is a female, the age of the patient, and the reason for the visit.

At the household level, it includes the sex and age of the household member, and for women a dummy indicating that the woman is literate. The results are robust whether or not these controls are included in the regression. We favor the results controlling for these characteristics since it improves the precision of the estimates. Finally, we clustered error terms at the health area level to take into account potential correlation between units in the same assignment unit.

5 Results

Accessibility of Health Services

Table 1 and 2 present the eects of PBF on the accessibility of health services: user fees, health facility opening, sta composition and attendance, oered preventive sessions at the facility and outreach activities.

Cost of Health Services

In Table 1, we nd consistent evidence that user fees for targeted services are lower in the PBF health facilities than in the xed-payment health facilities. The mean Summary Fee Index for targeted services of the PBF group is 1.08 standard deviations below distribution of the Summary Fee Index for targeted services by treatment status. We see a much lower proportion of health facilities at high fee levels and a higher concentration at low fee levels in the PBF group, suggesting that the decrease in the average fee index mostly results from the response of those health facilities which would oer high prices under a xed payment mechanism.

In contrast, the mean Summary Fee Index for non-targeted services of the PBF group is 0.4 standard deviations below the mean of the comparison group, a dierence which is not statistically signicant.

Figure 4 shows that the distribution of the Summary Fee Index for non-targeted services in the PBF group is quite close to the xed payment group. The health facilities thus strategically responded to the nancial incentive by a stronger reduction in the fees for the services that would bring a benet, without changing the fees for the other services.

The results found on user fees are robust when the information used comes from the households and patients straight out of consultation. We also nd that patients straight out of consultation paid 49% less for the drugs in the PBF health facilities than in the comparison facilities (the dierence is signicant at the 1% level).

Overall, the data consistently suggest that health facilities decreased the cost of targeted health services compared to what they would have done in the absence of PBF, plausibly as a strategy to attract more patients. Out of a list of 23 health services that could be oered, the typical health facility oers 14 [START_REF] Kohn | Punished by Rewards[END_REF] The average user fee is lower in the PBF group than in the comparison group for all the four targeted services, but the dierences are statistically signicant only for prenatal visits. The eect of PBF on user fees is strikingly large for all targeted services except birth delivery : we observe a 61% reduction in the fee for the second (or more) prenatal consultation (from 132 FC in the comparison group down to 52 FC in the PBF group) and a 48% reduction in the fee for the rst prenatal visit (from 850 FC in the comparison group down to 442 FC in the PBF group), both signicant at the 10 percent level. We also observe a 55% reduction in the fee for the rst curative consultation (from 1,263 FC in the comparison group down to 571 FC in the PBF group) but the dierence is not signicant. services 24 . PBF health facilities oer the same number of targeted and non-targeted services as in the xed payment group.

Health Facility Opening, Sta Composition and Sta Attendance

PBF did not change the composition of the sta within the facilities, neither the quantity of sta which amounts to 7 workers on average, nor the type of workers facilities generally count two thirds technical (doctors, nurses and birth-assistants) and one third non-technical workers (pharmacists, managers, secretaries, receptionists and maintenance workers). Doctors represent only 3% of total sta.

We nd higher sta attendance under PBF than under xed-payment in the unannounced visits in July, August and September 2012: 58% in the comparison group while 65% in the PBF group, a 14% increase signicant at the 10% level. Figure 9 shows the distribution of sta attendance at facilities by treatment status. We see that sta attendance is higher in the PBF group than in the xed payment group at any point of the distibution, suggesting that incentivized workers responded quite similarly to the incentive in terms of their presence. The higher attendance due to PBF echoes workers' statements in the qualitative interviews: If we work a lot, we will have more money and conversely , We need to work many days and hours in order to have more patients .

Preventive Sessions at Facilities Incentivized workers organized more preventive sessions at facilities in the last 12 months than non-incentivized workers (120 instead of 100, although the dierence is not signicant), a dierence which is signicant at the 5 percent level for targeted services (immunization, prenatal care and family planning): 74 preventive sessions were oered for these services in the comparison group, while 106 in the PBF group. For non-targeted services (postnatal care and VIH prevention), the number of preventive sessions is also higher in the PBF group but the dierence is not signicant 25 . Figures 5 and6 show the distribution of the number of preventive sessions for targeted services by treatment status. The positive eect of PBF on preventive sessions organized at facilities was thus concentrated on targeted services but did not happen at the expense of non-targeted services.

24 Curative consultations, pre and postnatal visits, birth delivery and preschool consultations are oered by more than 90% of health facilities. Immunization is oered by 88% and family planning by 84%. A smaller proportion of health facilities oer the other services.

25 It is important to notice that the supply for preventive sessions for targeted services is already much higher than the supply for non-targeted services (out of 100 preventive sessions in the last 12 months, 74 were devoted targeted services and 26 to non-targeted ones), so the eect of PBF widened the gap between targeted and non-targeted services.

Number of Outreach Activities in the Community

The number of outreach activities for targeted services is higher in the PBF group: health workers performed an average of 16 visits to the community in the last 12 months, while 10 in the xed payment group, which represents a 60% increase (the dierence is signicant at the 10 percent level. By contrast, the dierences in the number of outreach activities for non-targeted services between the PBF and the comparison groups is small and not signicant, suggesting no increase at all. Figures 7 and8 show the distribution of the number of outreach activities for targeted and non-targeted services by treatment status.

Overall, the accessibility of the PBF health facilities was improved via a decrease in user fees, an increased sta attendance and a larger number of preventive sessions organized at the facility and of outreach activities in the community.

Service Quality

Table 3 presents the eects of PBF on health service quality: technical quality, patients' understanding of diagnosis and prescriptions, and patients' satisfaction. While analysing the results on quality, it is important to keep in mind that this PBF approach did not tie payments to any quality measures.

Technical Quality of Health Services On average, patients report 16-minute consultations and household members report 17-minute consultations in the xed payment group. We don't observe any dierence induced by PBF in consultation time from the patients, but consultation time from the household members is found 20 minutes in the PBF group. This nding at least dispels the fear that incentives based on the quantity of health services would imply maximizing the number of patients at the expense of time spent with each of them.

The average compliance rate with standard medical procedures is found pretty low: 35% for classic patients, 67% for prenatal visits and 62% of postnatal visits. 40% of patients straight out of consultation also report that drugs were prescribed without them being examined. On average, women stayed three days in the health facility after giving birth. Overall, our data show that technical quality is poor and PBF had no impact on it.

Patient's Understanding of Health Services The understanding of diagnosis and next steps seems good: 83% of patients straight out of consultation declared that they understand the diagnosis and next steps and 90% knew what drugs they were supposed to take after the consultation.

Surprisingly, the PBF decreased the proportion of patients who understood which drugs they should take compared to the comparison group from 90% down to 83%. Most of household members (94%) also understood the diagnosis provided by the health worker but the PBF had no impact on this level of understanding.

Patients' Satisfaction Almost all patients 94% were satised by their visit at the health facility. The main reason for satisfaction is the quality of care (57%). The second reason is the quality of welcome (28%) (note that patients could give multiple responses). It is also worth noting that user fees and equipment quality were not important reasons neither of satisfaction nor of dissatisfaction. We nd a similar pattern of results for household members: 91% declared that they were satised, mainly thanks to the quality of care (74%). The quality of welcome was less considered as a satisfaction criteria (8%) and user fees and equipment quality were still not cited as major reasons of satisfaction or dissatisfaction. Patients thus seem surprisingly indierent towards the level of user fees. The PBF did not have any impact on the level of patients' satisfaction.

To conclude on service quality, we don't nd any consistent trend that allows us to conclude that the PBF improves the quality of health services. It is important to note that the PBF system implemented in Haut-Katanga was not based on any quality measures unlike other PBF systems.

Considering this, we could have expected both an increase in service quality as a strategy to attract patients, or some degradation in the quality of health services due to the focus put on the quantity of health services. None of it occurred, suggesting that workers' investment in service quality was not elastic to an incentive based on service volumes.

Health Service Utilization and Population Health Status

Table 4 presents the eects of PBF on health services utilisation and health outcomes.

As shown in Table 4, 50% of household members visited a health facility in the 12 months before the survey. PBF had a small negative eect on this proposition reducing it to 47% of the households members (the dierence is signicant at the 10% level). Unmet needs remain substantial: 25% of people in the population was sick and did not visit a health facility in the last 12 months (the other 75% being either not sick or sick but visited a health facility), without any signicant dierence under PBF or xed payment. Finally, household members who visited waited almost 4 days before the visit and PBF did not reduce the waiting time.

85% of children aged 0 to 5 received at least one immunization shot based on mother declaration, which is somewhat conrmed by a more objective measure of tuberculosis immunization:

the enumerators could see the TB immunization scar on the shoulder of 60% of children. The average number of immunization shots is 2.7 26 . We do not nd any eect of PBF on utilization of immunization.

82% of births in the last 12 months were attended in a health facility. Women who have been pregnant in the last 12 months got 3 prenatal visits and 1 postnatal visit at the facility 27 . Moreover, 38% of these women have been supplemented with iron and 54% have taken medication to prevent malaria. Finally, mothers breast-fed their child for ve and a half months on average. The PBF had no impact on these perinatal outcomes. It did not have any impact neither on the use of modern family planning: only 5% of women aged 15-49 use a modern contraceptive method 28 .

Overall, we can reject the idea that PBF increased service utilization, which is surprising given the eort made by the health workers to make health services cheaper and more accessible. Since our measure of service utilization covers 12 months preceding the endline survey, the absence of dierence in service utilization between the PBF group and the xed payment group relates mostly to the period when the incentives were in place, and incidentally to the period after the incentives were withdrawn. At baseline, health workers were found to spend numbers of hours in the facility for an average of only 2 patients per working day. Little demand for health services was thus a serious concern to start with. Reasons for the lack of response to lower user fees and improved accessibility could be that prices of health services work as signals for health service quality, or that people are reluctant to use health services because they do not fully understand its benets.

Outreach activities should help but only if health workers are trusted by the community, welltrained, and really take time to inform and convince the population about the benets of health services. From the qualitative interviews, we understand that the outreach activities were more focused on providing information about the schedule of preventive health sessions than on explaining in details the benets of the dierent services. Also, poor families face so many challenges a day causing stress and preoccupation that it might be dicult to carefully weight the costs and benets of health services and place health service utilization in the top priorities of the day. The important result is that the incentivized health workers were not in a position to identify and address the 26 Full immunization requires 5 shots, ideally before the child turns 2.

barriers to health service uptake, which might be particularly severe in the context of Haut-Katanga where the population is poor, low-education and generally uninformed about modern medicine. As a consequence, the indicators of health outcomes (general, maternal, under-5 and new-born mortality, and under-5 weight-for-height z-score) did not improve (see Table 4).

Health Facility Revenue

Table 5 presents the eects of PBF on the ressources at the facility level, the health worker's payment, and the overall quality of the facilities' infrastructure and equipment.

Total Resources at the Facility Level We nd 42% less total resources in the hands of PBF health facilities than comparison health facilities the month before the survey, signicant at the 5% level. The average revenue from user fees was half as in the comparison group (p-value 0.15), and the revenue from drugs and medical lab 54% lower (signicant at the 10% level). In contrast, we don't observe any dierence in fundings from the government nor NGOs. This result is consistent with our previous ndings that PBF led to lower user fees and price of drugs than xed payments without any increase in service utilization. According to the qualitative interviews, incentivized health workers who reduced their fees as a strategy to increase demand found themselves in a situation where they were not able to re-adjust their price schedule and raise prices back to their original values as the population had become accustomed to the reduced prices (even though utilization did not increase) and they were fearful of reducing demand to even lower levels.

Workers' Payment As a consequence, salary to health workers was signicantly lower in PBF health facilities than in comparison ones. We nd a 34% reduction in workers' total payment in the last month as reported by the facility head, and a 28% decrease as reported by the health workers (signicant at the 10% and 5% level respectively). Wages from the government are not statistically dierent in the PBF and the xed payment group, but we observe a signicant reduction in worker payment from the facility itself (which includes revenue from user fees and drug sales, and incidentally grants from NGOs). This result is thus consistent with the reduced user fees and drug prices observed in the PBF health facilities' revenue.

Quality of the Facility Infrastructure and Equipment We nd a signicant negative impact of PBF on the quantity and quality of equipment and infrastructure. The mean quality index in the PBF group is 0.53 standard deviations below the mean in the comparison group. Most of the twelve items included in this index indicate a lower quality of equipment in the PBF facilitiesnegative dierences are signicant for four items: lavabo, clean towels, sterilization material and the use of an examination table 29 . Furthermore, the mean equipment index in the PBF group is 0.64 standard deviations below the mean in the comparison group. The components of this index show that PBF facilities have consistently less equipment than the comparison ones. The dierences are signicant for four medical equipments: microscope, gynecological examination table, fridge and fuel.The day of the survey, the enumerator also checked the availability of ve common vaccines 30

and nine common drugs 31 . We nd non perfect although not so bad-availability of these products:

four out of ve vaccines and seven out of nine drugs were available in the health facility the day of the survey. In the last 12 months, 1.5 vaccines and 5 drugs had missed at least once in the health facility. The PBF had a negative impact on the availability of vaccines the day of the survey, with less than 3.5 out of ve vaccines available in the PBF group. However, it had no impact on the availability of vaccines for the last 12 months and on the availability of drugs, either on the day of the survey or in the last 12 months. These ndings are likely to be related to the reduced revenue in the PBF group. Because of the lack of resources, PBF health facilities had diculties in investing in new equipment and renewing the existing one.

Overall, PBF had a signicant and substantial negative impact on health facilities ressources, health workers salaries and health faclities infrastructure and equipment.

Sta Well-Being and Motivation

Sta Well-Being

Table 6 presents the eect of PBF on sta satisfaction, perceived workload, conicts and stress. All these outcomes are based on self-reported information so it is clearly subjective. Since we do not see any reason why social desirability bias would be dierent in the PBF and in the xed payment group, the comparison between the two groups gives evidence on how PBF aected sta subjective well-being.

Job Satisfaction PBF induced a 14% signicant decrease in the job satisfaction of facility sta going from 5.7 to 4.9 on a scale from 0 to 10. However, we do not nd an increase in the proportion of workers who would go for a position in another health facility. In the qualitative interviews, many health workers from the PBF group complained about the PBF system and the frustration they had from the ineciency of their strong eorts to increase the demand: If there is no patient, we can't do more than working 26 days . The lower job satisfaction is also likely to be related to the reduced worker salary.

Subjective Workload Overall, more than half of the facility sta nd their workload heavy (53%), feel that they had too much work last week (61%) and that they have been tired (56%) in the last seven days. The PBF decreased signicantly the perceived workload and fatigue: these three indicators decreased by respectively 16%, 28% and 16%. As shown in the previous section, this does not reect any dierence in the eective workload which is similar in both groups. The change in perception could be due to the disappointing impact of the eort facility sta made to increase the number of patients: the increased eort to attract patients made the lack of demand for health services more salient, which could also have contributed to the lower job satisfaction described above.

Conicts and Stress As PBF induces higher volatility of payments than xed payments, it could be a source of stress for the workers. In the comparison group, 39% of the workers declare that they worry about the volatility of their remuneration, whereas 49% in the PBF group (a 24% increase), and the dierence is close to signicant at conventional levels (p-value = 0.11). Actually, we see a large and signicant 72% increase in the proportion of facility heads who worry about the volatility of the payment in the PBF group, but no signicant increase among the other health workers (result by category of sta not shown). Importantly, this eect is not due to the lower remuneration 32 . In terms of conict, PBF should increase competition between and within facilities as payment distribution among health workers can be autonomously decided by the facility head.

Competition between health facilities was not perceived by the workers: 36% facility sta reported that the facility is in competition with other health facilities in the xed payment group, with no signicant dierence in the PBF group. As for internal competition, the workers declared a level of conict of 1.72 on a scale from 0 to 10, with no impact of PBF. To provide evidence on the 32 Workers worry about the level of their remuneration as much in the PBF group as in the xed payment group.

distribution of worker eort within facility and possible free-riding issue due to PBF, we compared the standard deviation of eort measures within facility: number of outreach activities performed in the last 12 months, number of hours worked the last day and the last week, number of patients consulted the last week and the last month. We don't nd any signicant dierence in the standard deviation of eort measures within facility (results not shown, available upon request). This nding suggests that there was not free-riding taking place despite the collective nature of the incentive, consistent with the lack of increase in conict within facility. However, 14% of the workers declared that the distribution of the payment within the facility was a source of conict, while 27% in the PBF group, but the dierence is not signicant (p-value=0.17).

Overall we observe a lower perceived workload and a lower satisfaction in the PBF group, both likely due to the disappointing impact of increased eort on the number of patients and worker salary. PBF also increased the proportion of facility heads who worry about the volatility of the payment but did not increase the level of conict within facilities.

Sta Motivation

Sta Motivation When the Incentives were in Place

As shown in Table 2, workers' eort to attract patients is larger under performance-based payment than xed-payment, which we interpret as an increase in worker motivation due the incentive.

Besides, we don't nd evidence that the collective nature of the incentive led to free-riding: the standard deviation of a number of eort measures at the worker level, like the number of outreach activities performed in the last 12 months, the number of patients in the last day or last week, or working time at the facility in the last day, week and month, was found statistically similar in the PBF and xed payment group (results not shown, available upon request).

Sta Motivation After the Incentives were Removed

Table 6 presents the eect of PBF on sta attendance after PBF was removed, and the proportion of workers who report material benets as the main advantage or disadvantage of the job.

Sta Attendance The positive eect of the incentive on sta attendance reversed at endline after PBF has been withdrawn. The interviewers did not announce the day they would arrive in the facility for the endline survey to avoid manipulation of sta attendance. Attendance rate in the xed payment group was found 57%, similar to before the payment was withdrawn: 58%. In contrast, a striking reversal happened in the PBF group where attendance rate was found 65% before the incentive was withdrawn while only 45% after. This represent a substantial reduction in the number of workers observed by the interviewer when s/he arrived: 3.8 in the comparison group while 2.5 in the PBF group (the dierence is signicant at the 5% level). Figure 10 shows the distribution of sta attendance at facilities after the pilot by treatment status. Sta attendance is lower in the PBF group than in the xed payment group at any point of the distibution, suggesting again that workers responded quite similarly to the end of the incentive 33 .

The nancial incentive thus induced higher worker total motivation compared to xed payments as long as the incentives were in place, but lower total motivation after the incentive was withdrawn.

It is important to keep in mind that worker attendance was found higher in the PBF group than in the xed payment in July, August and September 2012, when the depressing impact of PBF on user fee revenue and worker salaries had already taken place. Also, payments from the governement stopped in the PBF and in the xed payment group at the same time, which represents the same average reduction in health facilities' revenue by design. The reversal in sta attendance dierence between PBF and xed payment facilities thus happened in a context where facilities' revenue decreased by the same amount. Therefore, the reason for the reversal is unlikely to be driven by the level of worker income, suggesting a change in the structure of worker motivation.

Attention Paid to Material Benets In the xed payment group, 38% of workers mention spontaneously remuneration or material comfort as the main advantage or disadvantage of their position, as opposed to non material benets like social recognition or health benets to the population. This proportion increases dramatically to 51% in the PBF group (a 34% increase signicant at the 5% level). This nding suggests that exposure to PBF changed the salience of nancial motives in health workers' mind. Importantly, this change is also unlikely to be driven by the decrease in user fee revenue and workers' remuneration since we observe a signicant increase in the proportion of workers who mention nancial benets as the main advantage (from 11% to 17%, signicant at the 10% level), while a smaller and insignicant increase in the proportion of workers who mention nancial benets as the main disadvantage (from 29% to 35%, p-value 0.15). This nding gives evidence of a shift in attention from the intrinsic value that the worker attributes to her job in favor of the external benet. We interpret this eect as evidence that incentives can not 33 This result is consistent withdeclarative data from the workers: worker attendance rate in the last seven days is found 78% in the xed payment group while 71% in the PBF group (p-value of the test of equality 0.04).

only inform ignorant agents about some attributes of the task or their ability to perform, but also change the locus of control from internal to external by increasing the weight of external motives in worker utility.

To summarize the eects of PBF on worker motivation, we nd that: 1) When PBF is in place, worker's total motivation is higher under PBF (U 0 < U 1 ) despite the fact that worker salary from user fees are lower than under xed payments (F 1 < F 0 ); 2) After PBF is withdrawn, worker total motivation is lower in the group who was exposed to PBF (U 2 < U 0 ), which might be attributed to two facts: (i) Worker salary is lower than in the group who was under xed payments (F 2 < F 0 ); (ii) Attention paid to nancial motives relative to intrinsic motives proved more important (α 0 < α 1 ), and this change is not due to the decrease in worker salary.

Conclusion

This study examines a performance-based payment mechanism compared to a xed payment mechanism to health care providers in the district of Haut-Katanga, DRC. The performance-based payment studied was conditional on the number of patients for some pre-determined services, which is one specic approach of PBF. The ndings show that the performance-based mechanism led to increased eort by health workers to attract more patients for health services that were included in the performance measure, without crowding out non-targeted services and service quality, nor generating new conicts within the facilities. However, the increased eort made by the health workers did not lead to signicant changes in the utilization of health services by the population, leading to a very disappointing reduction in facility revenue and worker income. This nding suggests that health workers were not able to nd the successful strategies and innovate to change health-seeking behavior. A question is whether the lack of inventiveness and creativity required to increase demand for health services is due to the nancial incentive itself by focusing attention and limiting thecapacity to draw unusual connections between elements, as argued in the psychological literature, or due to the diculty of the task itself and the lack of skills and human capital of the health workers in this specic context. Importantly, we also nd that PBF created a shift in workers' attention from non-nancial to nancial motives apart from the reduction in worker income, and that workers decreased their eort after the incentive was removed. In terms of policy lessons, these nding suggest that nancial incentives should be used as a permanent policy rather than a temporary policy in order to limit the adverse eects of the motivational shift, and only in situations where the task is easy so that workers have the capacity to carry out the rewarded output.

The lack of response of the population challenges the idea that the demand for health services is elastic in all contexts: substantial decreases in prices were not able to encourage more demand, nor did improved accessibility. Specic interventions to stimulate demand for health may be combined with supply-side interventions like PBF. When asked about the reason for their (dis-)satisfaction in our survey, people proved mostly sensitive to service quality. One possibility would be thus to include service quality in the set of purchased performances as it was done in Rwanda, with the hope that health providers would engage into quality improvements that would attract more patients.

Alternatively, interventions to improve awareness about the benets of health products or to help people overcome behavioral issues like procrastination could supplement a PBF mechanism. We control for the urban/rural location of the health facility.

HEALTH FACILITIES' RESOURCES

Figure 1 : 1 Figure 2 :

 112 Figure 1: Performance-Based Financing in Africa

Figure 8 :

 8 Figure 8: Distribution of Outreach Activities for Non-Targeted Services, by Treatment Status

Figure 10 :

 10 Figure 10: Distribution of Sta Attendance after the Pilot, by Treatment Status

  A nal survey was administered in December 2012-February 2013, four months after the PBF mechanism was withdrawn. The endline survey was administered in 87 out of the 96 health areas involved in the experiment because the rainy season and the insecurity created by the Maï Maï insurgency made it impossible to reach the other 9 health areas. Attrition occurred at the same rate in both groups, with 44 health areas in the PBF group and 43 in the xed payment group present at endline. The endline survey entailed four questionnaires for the facility head, the health workers, patients straight out of consultation, and households living in the catchement area. All facilities in the 87 health areas that could be reached were interviewed, totalizing 123 health facilities. All the technical sta in each health facility was also interviewed up to ten persons 20 , totalizing 332 health workers.A sample of ten patients per facility was randomly selected for exit interviews, or the maximum available if fewer are present, totalizing 1,014 patients. Finally, the household questionnaire was administered to 1,708 households: 20 households were interviewed in each of the 87 health areas, among which 10 households randomly chosen in the population and 10 randomly chosen among the households with a pregnancy in the last 12 months 21 .

Table Appendix 2 reports the distribution of the endline sample across the treatment and the control groups. Table Appendix 3 shows some descriptive statistics on the endline sample.

  The quality index is based on direct observation by the enumerator when s/he arrived at the facility for the endline survey of twelve items: building material, waiting room, consultation room, lavabo, soap, clean towels, bathrooms, sterilization material, permanent display of user fees and drugs' costs, use of an examination table and ordinogram. The infrastructure index includes six items: phone ownership, motorized transportation mean ownership, access to clean water, toilet and electricity, and hard roof. Finally, the equipment index includes the quantity of fteen types of medical

equipment owned by the health facility: generator, sterilizer, tensiometer, stethoscope, baby-scales, weighing scale, height gauge, microscope, gynecological examination table, fridge, delivery boxes, fuel, kerosene, bed and solar panel.

Table 2

 2

presents the eects of PBF on health facility opening and sta attendance. Results show that PBF did not change the extent to which health facilities are open: 94% of patients and 87% of households report that they could consult every time they visited the facility. According to the facility heads, facilities open on average 30 days per month and 139 hours per week. These results suggest that health facilities are generally open and that the margin of improvement in this domain is almost nonexistent.

Table 1 :

 1 Eects on User FeesTargeted services: first curative consultation, delivery, and prenatal visits Fee Summary Index is the equally weighted average of z-scores of its components. The z-scores are calculated by subtracting the control group mean and dividing by the control group standard deviation. The components of the index are fees paid for first and second curative consultations, delivery, prenatal and postnatal visits, and preschool consultation.

	Average Treatment Effect (ATE)	p-value (ATE=0)	Mean of Dep. Var. (Control)	St.dev. of Dep. Var. (Control)	Observations

Non-targeted services: second curative consultation, postnatal visit, and preschool consultation Data Source: Endline survey. ***, **, * indicate significance at 1, 5, and 10%. Error terms are clustered at the health area level. We control for the urban/rural location of the health facility.

Table 3 :

 3 Eects on Service Quality Endline survey. ***, **, * indicate significance at 1, 5, and 10%. Error terms are clustered at the health area level. We control for the urban/rural location of the health facility.

	Average Treatment Effect (ATE)	p-value (ATE=0)	Mean of Dep. Var. (Control)	St.dev. of Dep. Var. (Control)	Observations

Table 4 :

 4 Eects on Service Utilization and Health Outcomes

	Average Treatment Effect (ATE)	p-value (ATE=0)	Mean of Dep. Var. (Control)	St.dev. of Dep. Var. (Control)	Observations

of Patients at Endline (After PBF was withdrawn)

  Endline survey. ***, **, * indicate significance at 1, 5, and 10%. Error terms are clustered at the health area level. We control for the urban/rural location of the health facility.

	At the Facility Level, Last Month
	Number of patients for targeted services	-61.714	0.628	605.6102	1194.306	112
	Number of patients for all services	-49.916	0.732	832	1378.686	109
	At the Health Worker Level, Last Month
	Number of patients for targeted services	-21.383	0.468	156.8494	176.6688	316
	Number of patients for all services	-29.925	0.387	239.3313	245.167	309
	Health Outcomes
	Weight-for-height z-score	-0.347	0.306	0.4450215	5.516395	2403
	Number of persons in the household who died in the last 12 months	.007	0.732	.1366313	.4006933	1708
	Number of women in the household who died for perinatal reasons in the last 12 months	-.004	0.427	.009434	.0967264	1707
	Number of children under 5 in the household who died in the last 12 month	.012	0.55	.0896226	.3171387	1707
	The child born is the last 12 month is still alive	-.01	0.093*	.9897751	.1007032	961
	Data Source:

Table 5 :

 5 Eects on Facilities' Total Ressources Endline survey. ***, **, * indicate significance at 1, 5, and 10%. Error terms are clustered at the health area level.

	Average Treatment Effect (ATE)	p-value (ATE=0)	Mean of Dep. Var. (Control)	St.dev. of Dep. Var. (Control)	Observations

Table 6 :

 6 Eects on Sta Well-Being and Intrinsic Motivation rate of workers in the facility in the last 7 days (as reported by the facility head) Endline survey. ***, **, * indicate significance at 1, 5, and 10%. Error terms are clustered at the health area level. We control for the urban/rural location of the health facility.

	Average Treatment Effect (ATE)	p-value (ATE=0)	Mean of Dep. Var. (Control)	St.dev. of Dep. Var. (Control)	Observations

This reallocation of attention away from other tasks was developed by[START_REF] Holmström | Multitask Principal-Agent Analyses: Incentive Contracts, Asset Ownership, and Job Design[END_REF] as the multitasking problem.

Two studies provide evidence that rewards contingent on a specic input (respectively attendance and service quality) do motivate health workers to provide more of this input (at least in the short run), but did not lead to any increase in health service utilization (the output)[START_REF] Banerjee | Putting a Band-Aid on a Corpse: Incentives for Nurses in the Indian Public Health Care System[END_REF][START_REF] Peabody | Financial Incentives and Measurement Improved Physicians' Quality of Care in the Philippines[END_REF].

PBF has commonly been a part of a package that may include increased funding, technical support, training, changes in management, and new information systems. In most studies, the level of resources allocated to the health facilities in dierent treatments is not similar, as well as the level of technical supervision and information system.

For the incentivized village committees, 20% of the grant depended on the relative performance of the village with respect to a set of educational and health outcomes. The study nds that the incentive led to an increase in health workers' attendance, better health outcomes, and an absence of negative spillovers on untargeted outcomes.

166 facilities were grouped into 8 pairs and one side of each pair was randomly assigned to pay-for-performance funding, while the other side continued with the traditional input-based funding until 23 months after study baseline.The paper uses a dierence-in-dierence strategy in order to control for potential selection eects since the number of units of randomization was very small and some post-randomization reassignment of some districts happened because of administrative boundaries' reorganization.

The literature is more developed in the context of high income countries, although identication issues also limit the scope of many studies. For instance, Mullen, Franck and Rosenthal (2010) use a dierence-in-dierence strategy on US data and show that pay-for-performance did not lead to any major improvement in quality nor notable substitution eect of non-rewarded services for rewarded ones.

For instance, increased use of prenatal visits might not lead to a reduction in child mortality if mothers do fewer postnatal visits

After some periods, the agent may observe that her eort is de facto not as much productive as expected as adjust her eort accordingly.

Note that the number of pre and postnatal visits outside the facility, by healers or den mothers, seems quite low since including those visits in the count does not increase much the number of visits.

Modern contraceptive methods are pill, shot, condom, IUD, spermicidal, implant and sterilization.

However, it is worth noting that PBF facilities are more likely to permanently display the user fees and drugs' costs in the facility.

Vaccines: DTaP, Poliomyelitis, BCG, Measles and Yellow Fever.

Drugs: oral rehydration salts, paracetamol, co-trimoxazole, ampicillin, metronidazole, quinine sulfate, mebenda- zole, tetracycline and Ringer's solution.

We wish to acknowledge the support of the World Bank. Jean-Jacques Frère and Hadia Samaha led the implementation of this project and we are grateful to them for their leadership. We thank the Health Authorities of Haut-Katanga and the Health Sector Rehabilitation and Support project (Projet d'Appui à la Réhabilitation du Secteur de la Santé -PARSS) in Lubumbahi and Kinshasa for their collaboration. We are deeply indebted to Julie Berthet-Valdois for outstanding project management, and to the Ecole de Santé Publique de Lubumbashi for excellent data collection. We also thank Saidou Ouedraogo for excellent assistance with data entry.