Andrew E Clark
email: andrew.clark@ens.fr

David Masclet
email: david.masclet@univ-rennes1.fr

Marie-Claire Villeval
email: villeval@gate.cnrs.fr.

Alan Krueger

George Loewenstein

Andrew Oswald

Effort and Comparison Income Survey and Experimental Evidence

Keywords: M54, J33, A13, C92, D63 Effort, Comparison Income, Rank, Income distribution, Peak-End, Experiments

This paper combines ISSP survey data and experimental evidence from a giftexchange game to determine the effect of status or relative income on work effort. We find a strong effect of others' incomes on individual effort decisions in both datasets. The individual's rank in the income distribution has a more powerful effect on effort than does others' average income, suggesting that comparisons are more ordinal than cardinal. We further show that, controlling for own income and income rank, the width of the relevant income distribution matters, with effort increasing in the distance from the bottom of the income distribution. Last, effort is also affected by comparisons over time: those who received higher income offers or had higher income rank in the past exert lower levels of effort for a given current income.

Résumé Cet article compare les données de l'enquête ISSP et celles issues d'un test expérimental d'un jeu d'échange de dons, afin d'identifier l'effet du statut et du revenu relatif sur l'effort au travail. Nous observons un effet important du revenu d'autrui sur les décisions d'effort individuelles dans les deux bases de données. Le rang de l'individu dans la distribution des revenus a un impact plus important sur l'effort que le revenu moyen des autres, ce qui suggère que les comparaisons sont davantage ordinales que cardinales. Nous montrons en outre que, contrôlant pour le revenu et le rang personnel, l'étendue de la distribution des revenus au sein du groupe de référence compte, l'effort individuel étant d'autant plus élevé que le revenu est éloigné du bas de la distribution. Enfin, l'effort est aussi affecté par les comparaisons inter-temporelles : ceux qui ont perçu des revenus plus importants ou ont bénéficié d'un rang plus élevé dans le passé exercent un effort plus faible à revenu courant donné.

Introduction

One of the perhaps rare subjects that has inspired research across a variety of social science disciplines is that of status or social comparisons. A growing literature in economics has been devoted to the role of comparisons in explaining a number of behaviors, including financial market behavior [START_REF] Campbell | By Force of Habit: A Consumption-Based Explanation of Aggregate Stock Market Behavior[END_REF], criminal activity [START_REF] Glaeser | Crime and Social Interactions[END_REF], or subjective well-being [START_REF] Clark | Satisfaction and Comparison Income[END_REF][START_REF] Brown | Does Wage Rank Affect Employees' Wellbeing?[END_REF][START_REF] Ferrer-I-Carbonell | Income and Well-Being: An Empirical Analysis of the Comparison Income Effect[END_REF][START_REF] Luttmer | Neighbors as Negatives: Relative Earnings and Well-Being[END_REF]).

One part of this literature has focused on the relationship between relative income and labor market behavior. Quits have been shown to be negatively correlated with the average wage in the firm for similar workers [START_REF] Galizzi | Relative Wages, Wage Growth and Quit Behavior[END_REF]); women's labor force participation is influenced by relative income (specifically, whether the woman's husband earns less than the woman's sister's husband: [START_REF] Neumark | Relative Income Concerns and the Rise in Married Women's Employment[END_REF]; and rank in the local income distribution is a good predictor of migration [START_REF] Stark | Migration Incentives, Migration Types: The Role of Relative Deprivation[END_REF]. These behaviors mostly concern job choice. However, little is known about the impact of relative income on employee effort within the job, although efficiency wage theories are built on the concept of income comparisons between co-workers and justify wage compression via equity concerns [START_REF] Akerlof | The Fair Wage -Effort Hypothesis and Unemployment[END_REF][START_REF] Frank | Are Workers Paid Their Marginal Products?[END_REF].

In this paper we try to fill this gap. We analyze the influence of income comparisons on effort using both survey and experimental data. We suggest that such income comparisons may explain why some of the empirical evidence on the wage-effort relationship is mixed. It is commonplace to assume that wages have both incentive and selection effects [START_REF] Prendergast | The Provision of Incentives in Firms[END_REF][START_REF] Lazear | Performance Pay and Productivity[END_REF] and that reciprocity motivates employees to respond to high wages by greater effort [START_REF] Akerlof | The Fair Wage -Effort Hypothesis and Unemployment[END_REF][START_REF] Fehr | Does Fairness Prevent Market Clearing? An Experimental Investigation[END_REF]. Empirically, however, higher wages are not always associated with higher effort [START_REF] Gneezy | Pay Enough or Don't Pay at All[END_REF]. This is explained by a crowding-out effect of monetary rewards on intrinsic motivation [START_REF] Frey | The Cost of Price Incentives: An Empirical Analysis of Motivation Crowding-Out[END_REF], supra-optimal motivation generating choking under pressure [START_REF] Ariely | Large Stakes and Big Mistakes[END_REF][START_REF] Baumeister | Choking under Pressure: Self-Consciousness and Paradoxical Effects of Incentives on Skillful Performance[END_REF]), or an earnings target which bounds effort at some threshold [START_REF] Camerer | Labor Supply of New-York City Cab Drivers[END_REF]. Here, we suggest that under social comparisons, individual effort level will depend on both income and position in the income distribution. In the context of worker effort, this reference income produces classic omitted variable bias.

We introduce an explicit measure of reference group income into both survey and experimental data to isolate the effect of income comparisons on worker effort. There is a strong correlation between work effort and own income in all of our specifications. We also identify robust effects of income comparisons on effort supplied at work: those who are relatively well-paid work harder.

Given own income, we test which of relative income (i.e. the ratio of own income to comparison income) and income rank in the reference group is most important in determining effort: in other words, are social comparisons cardinal or ordinal? We further ask whether individuals compare up (to those who earn more), or down (to those who earn less), or both. Last, we consider whether income comparisons are not only horizontal (i.e.

to other individuals at the same point in time) but also intertemporal, so that changes over time in the individuals' own income or rank matter in determining their effort at work. Many find the idea of social comparisons seductive, but conclusive empirical proof of their existence has been elusive. This is partly because it is difficult to know to whom individuals compare, and because individuals' behavior may be correlated within a group, not because they compare to each other, but because they are exposed to common unobserved environmental factors [START_REF] Manski | Identification of Endogenous Social Effects : The Reflection Problem[END_REF]. Our empirical strategy for analyzing social comparisons in effort decisions allows both of these criticisms to be side-stepped.

Evidence is based on both experimental and survey data.

The experimental approach has the advantage of defining a priori the reference group, rather than having to infer it from survey data 1 , and of avoiding any possible role for contextual effects. In addition, it relies on actual and costly decisions instead of subjective reported behavior. Survey data, on the other hand, has the clear advantage of larger sample sizes, and avoids the criticism that laboratory experiments are to an extent unrealistic, either because participants are unrepresentative, or because behavior in an experiment is not typical of that in real life. The joint use of both survey and experimental data is still very recent [START_REF] Fehr | A Nation-Wide Laboratory. Examining Trust and Trustworthiness by Integrating Behavioral Experiments into Representative Surveys[END_REF][START_REF] Brown | Does Wage Rank Affect Employees' Wellbeing?[END_REF][START_REF] Carpenter | Do Social Preferences Increase Productivity? Field Experimental Evidence from Fishermen in Toyama Bay[END_REF][START_REF] Cummings | Effects of Tax Morale on Tax Compliance: Experimental and Survey Evidence[END_REF] and can be seen as a joint test of robustness. If there are consistent patterns in both types of data, we can have greater confidence in the external validity of laboratory experiments.

Our survey data come from the 1997 wave of the ISSP (International Social Survey Program). This survey includes data on both earnings and self-reported discretionary effort. We examine the correlation between effort and both reference group average earnings, and income rank within the reference group.

Our laboratory experiment extends the gift-exchange game between an employer and an employee, as introduced by [START_REF] Fehr | Does Fairness Prevent Market Clearing? An Experimental Investigation[END_REF], by allowing income comparisons between employees from various firms. The reference group for employees in this experiment consists of other employees participating in the same experimental 1 More problematically, even if we are sure about the reference group, we have to suppose that individuals know what others earn. Alan Krueger (personal communication) has carried out work asking people in two companies to identify another employee at the company that they were close to and then to estimate that person's wage. The correlation between this estimated wage and what the other employee actually earned (using the company's payroll records) was low.

session and placed under similar experimental conditions. All employees have the same cost of effort function. In contrast with recent attempts to show how co-workers' wages within firms affect effort [START_REF] Güth | Fairness within Firms: The Case of One Principal and Multiple Agents[END_REF][START_REF] Charness | Do Co-Workers' Wages Matter? Theory and Evidence on Wage Secrecy, Wage Compression and Effort[END_REF], we set up firms with only one employee, and a reference group consisting of other identical employees in different firms. In the first stage of this game, the employer offers a wage contract. In the second stage, employees who accept the contract decide on their effort level. In one of the treatments (the Information Treatment) we can identify income comparisons, as we inform employees, before they choose their effort level, about the wages offered by a sub-set of other employers in the labor market. In the Benchmark Treatment no such information is given. Both treatments are conducted according to a perfect stranger matching protocol. This game is well-suited to study how income comparisons affect the extent of reciprocity between employers and employees. 2We have four key findings. First, both the survey and experimental data show that individual effort depends not only on own incomes but also on relative incomes. This stands in sharp contrast to standard economic analysis of the income-effort relationship.

Second, rank in the income distribution matters more than the level of relative income. This suggests that comparisons are more ordinal than cardinal. Third, both survey and experimental data provide some evidence that individuals are more sensitive to downward than upward comparisons. The greater the distance of own income to the minimum income in the reference group, the higher the level of effort, at a given income level and income rank. Last, income is compared over time. For a given current income and income rank, effort is lower the higher the maximum income the individual received in previous periods; an analogous result is found for past income rank.

The paper is organized as follows. Section 2 surveys the literature on social comparisons, utility and behavior. Section 3 presents the empirical strategy with respect to both the ISSP survey data and the laboratory experiment. Section 4 reports the results from both data sources, and Section 5 discusses these results and concludes.

Literature

The existing literature on social interactions or comparisons can be broadly divided up into two strands: that on behavior and that on utility. This division can be illustrated by a direct utility function:

U i =U(a i , a j , ...) for j≠i (1)
which (most often) gives rise to a decision rule for i's utility-maximizing choice of a as:

a* i = f(a j , ....) (2)
The behavior and utility approaches to social interactions attempt to find empirical counterparts to (2) and (1) respectively.

There are a number of drawbacks to the behavioral approach. First, data on behavior is not always particularly accurate. Second, behavior often reflects the intersection of supply and demand, whereas we are interested here in individuals' preferences. Lastly, under separability conditions3 , others' behavior can affect my own utility, but not my behavior. There are equally problems with the utility approach, via equation (1): in particular, we do not necessarily know how to measure individual utility, U i .

Interactions in behavior have been widely modeled econometrically despite the identification problems emphasized by Manski (1993). 4 Many of these studies have concluded that social interactions do indeed influence behavior, in the sense that if you do more of something, then I am likely to do more as well. One interpretation is that this reflects a concern for status or relative standing. Another is the possibility that individuals might be learning from each other about how pleasant or dangerous goods or activities are (so that their behaviors are correlated), rather than caring about their status. Rival explanations emphasize the perhaps key role of common omitted variables such as contextual effects, although much care is typically exercised in the empirical literature to defuse this interpretation.

An alternative approach appeals to proxy measures of utility, such as life satisfaction, job satisfaction, and happiness. Perhaps because of a scarcity of surveys which measure both proxy utility and behavior adequately, most attention has been concentrated on the role of income comparisons in the utility function. Empirical estimation has thus mostly been based on the indirect utility function, testing specifications such as V i =V(y i , y j , ...) for j≠i (3) rather than its direct counterpart (1) above.

Both the behavior and utility approaches require that the reference group be identified:

to whom does the individual compare? There are a number of potential candidates, including the individual's peer group (those who share the same characteristics), others in the same household, spouse/partner, friends, neighbors, work colleagues, and the individual herself in the past.

An approach to modeling social comparisons which combines both of the above would be to consider behavior as a function of both absolute and relative income a i =a(y i , y j , ...)

which can be operationalized empirically as

a i = A 0 + βy i + φy j + γ'X i + ε i (5)
This is the approach that we take in this paper. If only own income matters in explaining i's behavior, then the estimated value of φ will be insignificant. On the other hand, if relative income is important in explaining behavior, then both β and φ will be significant. If action a is normal then we expect β > 0 and φ < 0.

The behavior we consider here is effort expanded at work: we ask whether workers' effort depend on how much others earn, modeling

e i =e(y i , y*, ...) (6)
where we expect e 1 > 0 but e 2 < 0. Here y* is considered to be some transformation of the income vector of other people who are in individual i's reference group. Equation ( 6) follows naturally from [START_REF] Adams | Toward an Understanding of Inequity[END_REF] equity theory, which states that, for person i and person j, individuals endeavor to ensure that the following equality holds:

Outcome j / Input j = Outcome i / Input i (7)

The idea is that individual i has a comparison or reference person or group, j, and reduces his or her own input or effort until the ratio of their own income to effort is in line with that of the reference person.

Much of the efficiency wage literature is also based on the idea of the comparison of one's own wage to those of co-workers [START_REF] Akerlof | The Fair Wage -Effort Hypothesis and Unemployment[END_REF] or of workers in other firms [START_REF] Summers | Relative Wages, Efficiency Wages, and Keynesian Unemployment[END_REF][START_REF] Johansen | Efficiency Wages, Interfirm Comparison and Unemployment[END_REF]. However, empirical evidence that workers' effort does in fact depend on relative income remains slight.5

A recent literature in experimental economics examines the effects of social comparisons among co-workers. In the first stage of the game proposed by [START_REF] Charness | Do Co-Workers' Wages Matter? Theory and Evidence on Wage Secrecy, Wage Compression and Effort[END_REF], a principal can propose different wages to her two employees. These employees may have either homogenous or heterogeneous ability levels, but the direction and magnitude of these differences are unknown to employees. In the second stage of the game, employees choose their level of effort. According to the treatment, wages are either public or private. Income comparisons are shown to affect only weakly employees' behavior, whereas firms reduce any income difference between co-workers for fear of retaliation from the lower-paid employee in terms of effort. In other words, firms anticipate a negative effect from income comparisons on effort that is not actually observed in workers' behavior. This wage compression effect was also observed by Güth, Königstein, Kovacs and Zala-Mezo ( 2001) in a principal-agent game in which information about the contracts offered to each employee is manipulated. They show that principals tend to reduce the income differential between employees when contract information is made public.

In these experiments, productivity differences are introduced between co-workers in order to motivate firms to vary their wage offers. The weak reaction by employees to subsequent income comparisons may show that productivity differences are considered as a fair source of income differentials. In our experiment, on the contrary, all employees have the same productivity, each firm only employs one worker, and income differences result from firms' various choices (and not from any skill differences between workers).

Gächter and Thoeni (2005) provide another experimental test using the strategy method:

subjects are asked to report their effort decision in reaction to various hypothetical income distributions. They identify a large subset of individuals who reduce their effort when faced with income inequality. In our experiment, incomes are actually chosen by real firm-subjects, and we infer the influence of income comparisons from individuals' observed effort decisions.

Empirical strategy

Our empirical strategy is based on the joint use of survey data and experimental data produced in the laboratory.

Survey Data on Work Effort

Our survey data, multi-country and cross-section, come from the 1997 Work Orientations module of the International Social Survey Programme, the ISSP (http://www.issp.org).

The key variables in our empirical analysis are effort, earnings and hours of work.

Individual yearly labor market earnings are converted to U.S. dollars using Purchasing

Power Parities from the OECD. Hours of work are measured at the weekly level.

Our dependent variable is effort at work. In the ISSP, this is crafted to measure discretionary effort, and is thus arguably well-suited to our analysis. All those in employment are asked to indicate the extent to which they agree with a number of statements. One of these is: "I am willing to work harder than I have to in order to help the firm or organization I work for to succeed".

The weighted distribution of answers to this question in the 1997 ISSP is shown below in percentages. We are interested in describing differences in the response to the effort question between individuals. A first pass is to look at the cross-country pattern in discretionary effort. To do so, we allocate a value of 5 to "strongly agree" through to a value of 1 for "strongly disagree" to the answers to the first effort question. Table 1 shows the number of observations and mean effort, ranked by country from the lowest to the highest effort. There are a certain number of limitations to this survey-based approach. One salient point is that income is measured with a certain amount of error in surveys. More specific 6 There is a strong correlation between unemployment and the mean of this effort variable. The average OECD standardised unemployment rate in 1997 of the lowest seven countries in the ranking was 12.3%, as against 5.9% for the ten highest-ranked. Both the Pearson and Spearman correlations between mean effort and the unemployment rate are significant at better than the 2% level. One interpretation is that social reciprocity allows firms and employees to attain Pareto-superior employment outcomes. 7 See for example van de Stadt, Kapteyn, and van de Geer (1985). A summary of the whole Leyden research programme in poverty and well-being is provided by [START_REF] Van Praag | The Measurement of Welfare and Well-Being: The Leyden Approach[END_REF].

Strongly agree

to this paper's concerns, the effort measure is self-reported rather than being observed directly. Last, we have posited a certain reference group (by country, gender, education, and age), but we cannot be sure that this is the most relevant one. For these reasons, we complement our survey analysis with experimental evidence on income and effort.

Experimental Design

The game We identify the impact of income comparisons on effort using a version of the standard gift-exchange game [START_REF] Fehr | Does Fairness Prevent Market Clearing? An Experimental Investigation[END_REF]. Each session involves twenty subjects who are divided into two groups, ten in the role of firms and ten in the role of employees. Roles are attributed at random and are kept constant throughout the session. All employees have the same characteristics, in contrast to [START_REF] Güth | Fairness within Firms: The Case of One Principal and Multiple Agents[END_REF] and [START_REF] Charness | Do Co-Workers' Wages Matter? Theory and Evidence on Wage Secrecy, Wage Compression and Effort[END_REF]. Workers do not differ in ability and they do not have to form beliefs about the relationship between incomes and other employees' productivity. A Benchmark Treatment and an Information Treatment have been designed.

The Benchmark Treatment consists of the standard gift-exchange game. In each of the ten periods of the game, each firm is matched randomly with an employee. Each period consists of two stages.

In the first stage, the firm offers a contract consisting of a wage [ ] 20,120 w ∈ [ to its employee. In the second stage, the employee decides whether to accept or reject the contract. If the contract is rejected, both the firm and the employee receive nothing.

Upon acceptance, the employee has to choose his level of effort, ] 0.1,1 e ∈

. The higher the level of effort, the higher the firm's profits but the greater the effort cost c(e) borne by the employee. This effort cost is convex, as shown in Table 2.

( ) P v w e π = -
where v is an exogenous redemption value; in our experiment, v=120. The employee's payoff is:

( ) A w c e π = -
-20

with a fixed labor market participation cost of 20 (corresponding to travel costs, say).

These payoff functions are common knowledge. At the end of the period, the firm is informed about the level of effort chosen by the employee, and both the firm and the employee are informed about their respective payoffs. In each new period, the pairs of firms and employees are randomly reshuffled. We implement a perfect stranger matching protocol so that no subject is with another subject more than once, and this is made common knowledge in the instructions. This allows us to rule out any reputation-building behavior [START_REF] Gächter | Reputation or Reciprocity?[END_REF].

The Information Treatment has the same structure. The difference lies in the fact that at the end of the first stage, after the firm's income offer is revealed, the employee is told about the income offered by four other firms to their employee in the same period.

Employees can thus compare their own income to the income offered to other a priori similar employees on the labor market (but not co-workers) before rejecting or accepting the contract and thus before choosing a level of effort. In contrast, the firm is not informed about the other firms' income policies. We choose to display only partial information about other income offers (in each period, four other randomly chosen income offers, instead of the whole distribution) to produce a greater variety of income distributions within the reference group. However it might be possible that, in both treatments, income and effort be above the theoretically predicted levels. Indeed the literature has shown that an employee typically reciprocates a high (low) income offer by choosing a high (low) effort level that increases (decreases) her firm's payoff [START_REF] Fehr | Reciprocity as a Contract Enforcement Device: Experimental Evidence[END_REF]Fehr, Kirchsteiger, and Riedl 1998) 9 . In addition, it is also possible that information about the income distribution may affect the effort level in the Information Treatment if individuals are sufficiently sensitive to income comparisons. If subjects make horizontal comparisons (i.e. among employees), we may expect that effort will be positively correlated with both relative income and income rank. On the contrary, as firms are never informed about the income distribution, there is no reason why their behavior should differ across treatments. 10

Equilibrium of the game

Procedures The experiment was conducted in the experimental laboratory of GATE, Lyon, France, using the Regate software [START_REF] Zeiliger | A Presentation of Regate, Internet Based Software for Experimental Economics[END_REF]. A total of 120 undergraduate students, from three local Engineering and Business schools, participated in one of the six sessions we organized. Two of these concerned the Benchmark Treatment and four the 9 One might argue that individuals may also reciprocate higher income rank and higher relative income with higher effort in the Information Treatment. However, in our experiment, firms were never informed about the income distribution. As a consequence, ranking could not be considered as intentional on the part of the employer. 10 A firm cannot know whether a lack of reciprocity is due to comparisons or to the employee's selfishness.

Information Treatment. No-one participated in more than one session. Upon arrival, the subjects drew a label from an envelope, indicating the name of their computer. The instructions (see the Appendix) were distributed and read aloud. The subjects then filled out a questionnaire which allowed us to check their understanding of the rules of the game. Questions were answered in private.

The subjects subsequently discovered their role (firm or employee). t-test, p<.0001) but there is no significant difference in average income between the two treatments. Firms do anticipate reciprocity from their employees, but they do not expect comparisons between them. Each employee made 10 contract acceptance decisions and, if the contract was accepted, chose an effort level. 11 The next section concentrates on the analysis of these effort decisions.

Each session lasted one hour on average, including the payment that was carried out in a separate room. Each subject earned on average €14 from the experiment.

Results

Effort may be influenced by relative income or income rank, by the width of the income distribution, or by the income the individual received in the past if there are intertemporal comparisons.

Effort and comparison income

We estimate discretionary effort equations on both datasets to determine whether income Table 3 shows that minimum effort was chosen 98 times out of 180 accepted contracts (54.4%) in the Benchmark Treatment, and 214 times out of 378 accepted contracts (56.6%) in the Information Treatment. 13It is also noticeable that social motivations lead employees to reciprocate higher incomes with greater effort as usually observed in the gift exchange game [START_REF] Fehr | Reciprocity as a Contract Enforcement Device: Experimental Evidence[END_REF]Fehr, Kirchsteiger, and Riedl 1998). We find a positive relationship between income and effort in both treatments, as shown by the mean income per effort level in Table 3. While the income-effort relationship looks steeper in the Information Treatment, the joint presence of income and comparison income makes such bivariate conclusions untrustworthy. The effort regression results are reported in Table 4 below. The first two panels correspond to the two different ISSP effort measures, and the third to the effort decisions in the Information Treatment of our experiment. Each panel consists of three regressions.

The first regression controls for own income or income and hours of work. The second regression adds the normalized income rank: a higher value of this rank variable thus corresponds to a higher position in the reference group income distribution. The third regression replaces income rank by average reference group earnings.

In the ISSP data we also control for age, gender, education and marital status, and country dummies. In the experimental data we only control for gender since there is little variance in age, marital status and education. In the latter, we also include a "period 1" dummy variable, which takes the value 1 for the first period of the game and 0 otherwise, to account for a possible learning effect, and a "period 10" variable, which takes the value 1 for the last period of the experiment and 0 otherwise, to pick up end-game effects.

Lastly, we control for a possible experience effect, with a dummy variable for having already participated in an economics experiment. giving a rank/income elasticity of 1.6. This higher elasticity may reflect the wider distribution of income in the survey data, the fact that rank matters more "in real life", or that rank is more important when reputation-building is possible.

The evidence from both survey and experimental data thus points to income position within the reference group as being an important determinant of how much discretionary effort workers provide, over and above the actual income they receive, which latter has been the focus of the literature to date.14 This, to our knowledge, is one of only a small number of empirical findings pointing to relative income and status as a determinant of employees' behavior.

In the third column in each panel, average reference group income attracts a negative coefficient in two out of three regressions, but is not significant except in the experimental data. If we include both the normalized rank and the reference earnings in the third regression (not reported here), this marginally significant effect disappears, whereas the coefficient associated with rank remains significant. Our second key result is therefore that ordinal comparisons, as measured by normalized rank in the income distribution, are a more powerful predictor of employee behavior than cardinal comparisons, i.e. the differences in earnings expressed in currency units. 15Other results in Table 4 show that effort increases with hours of work in the ISSP data.

Also effort is higher for the married and the higher-educated. The estimates on the country dummies (not shown) largely reproduce the effort ranking in Table 1. Table 4 also shows that effort in experimental data is higher in the first round, and lower, but not significantly so, in the last round. There seems to be learning at the beginning of the game but no end-game effect. Last, those who have already participated in an experiment in the past exert lower levels of effort. 16The estimated coefficients on the male variable are of interest. These are positive and significant for the first ISSP effort variable (willingness to work hard). However, men are far less likely to agree with the statement that they work so hard that it interferes with their life. Rather than seeing this as a contradiction, we believe that this is a manifestation of the sharp differences in the time that men and women devote to domestic work. In the experimental effort regression, the male dummies are negative but not significant.

Upwards and Downwards Comparisons

Table 4 showed that individuals are motivated by both absolute and relative income. The specification in Table 4 treated all individuals as being equally important -they all contribute to mean income and to rank in the same way. However, it is also useful to ask if comparisons are symmetric upwards and downwards: Are some people more salient for comparisons than others?

This is easiest to see in the experimental data, where each individual is confronted with four other income offers that have been made to workers like herself before making her own effort decision. We estimate random effects Tobit models with own income and income rank, and look for up/down asymmetries by separately introducing the value of the minimum income in the distribution and the maximum income in the distribution.

We proceed in the same spirit in the survey data. Here, within each reference group, we calculate the income values corresponding to the 25 th and 75 th percentiles.17 These are added separately to the effort regression which controls for income and income rank within the reference group. We also include controls for gender, age, education level, marital status, and country dummies.

If individuals are only sensitive to the first moment of the income distribution, then we expect these new variables to be insignificant. If, however, they respond to the spread of the distribution then we may expect some effect of these new variables on effort. In addition, if individuals are more sensitive to the bottom of the distribution than to the top (or vice versa), then the estimated coefficients on the two new variables will not be equal in absolute size. The results are in Table 5. With the introduction of income dispersion, own income and income rank remain positive and significant in both the survey and experimental effort equations. The dispersion measures themselves are only significant in one direction: downwards. In the ISSP data, individuals report working harder the greater is the distance between their own income and that of the 25 th percentile. In the experiment, effort reciprocity is greater the larger the distance between the individual's own income and the minimum income revealed in the information treatment. It is worth emphasizing that these effects occur at given levels of both income and income rank.

These results emphasize the role of the income distribution, given the individual's position in it, in determining effort. If rank matters, then every point in the income distribution potentially affects workers' effort. Table 5 suggests that there is an additional asymmetric distributional effect from incomes towards the bottom of the distribution.

Comparisons seem more important downward than upward: individuals work harder when their income or rank is high, and when those beneath them are some distance away. This is consistent with loss-aversion in income rank.

Effort and Past Income

The results so far have discussed the relationship between comparison income and individual effort. Here we turn to comparisons to the income that the individual herself received in the past. The broad idea, as in the addiction literature, is that past exposure to higher incomes may reduce the utility associated with current incomes and thus decrease the current level of effort. This hypothesis has been tested with measures of satisfaction in panel data (see [START_REF] Clark | Are Wages Habit-Forming? Evidence from Micro Data[END_REF][START_REF] Weinzierl | Estimating a Relative Utility Function[END_REF]), but not with measures of behavior such as effort. In parallel, a separate literature on time-inseparability in behaviors such as consumption and labor supply has developed.

One difficulty in these literatures has been to ensure that ceteris paribus holds over the long time-periods between waves. Experimental data are ideally-suited to testing models of habituation since we impose the same environment over time, especially in the perfectstranger framework where there is no role for reputation building. We therefore investigate the role of previous income in determining current levels of effort, by estimating random effects Tobit models with the experimental data only. Our a priori is that a higher past income will reduce current effort, with past income acting as a benchmark.

We pick up the effect of past income by including the running maximum income and the running minimum income as additional explanatory variables. That is, does effort at time t depend on the highest (lowest) income the individual had been offered up to and including time t? We carry out an analogous analysis with respect to rank to determine whether effort is influenced more by past income or by past income rank. This running maximum/minimum specification is inspired by the peak-end transformation, which has been used to model how a flow of pain is converted into a final global evaluation [START_REF] Redelmeier | Patients' Memories of Painful Medical Treatments: Real-Time and Retrospective Evaluations of Two Minimally Invasive Procedures[END_REF]. 18 The regression results are shown in Table 6. Table 6 shows that the past matters: for a given income and a given income rank, effort is significantly lower the higher is the most generous income offer received in the past (column 1), and the higher is best income rank achieved in the past (column 2). The running minima of income and rank do not seem to matter (although the positive coefficient on running minimum is almost significant at the ten per cent level). High income and high income rank seem to be particularly salient, however, and this evidence suggests that they are used as benchmarks with which to evaluate the current offer's generosity, and thus the degree of reciprocity. The last regression in column 3 considers running maximum/minimum income and rank together and indicates that the past best position in the distribution matters more than the past best absolute income. Including the reference income in the regressions (not shown) does not change the level of significance of these key variables.

Discussion and Conclusion

Evidence for the role of status or comparisons in determining behavior remains elusive.

In this paper we have looked for effects of income comparisons on discretionary work effort in both ISSP survey and experimental data. We have four key findings.

First, effort at work depends both on the individual's own income, and on what others earn, both in survey and experimental data. Our results thus contribute to the still small literature showing that comparisons affect behavior via actual costly decisions and not only utility via self-reported well-being. We further believe this to be one of the first papers to combine survey and experimental data to do so.

Second, income rank (i.e. first, second, third in the relevant distribution) is a better predictor of effort decisions than is average reference group income. As such, comparisons are ordinal rather than cardinal.

Third, we suggest that the width of the income distribution matters independently of the individual's own position in it. Holding absolute income and income rank constant, individual effort is higher the greater the distance to the bottom of the distribution;

distance to the top of the income distribution did not matter. To this extent, income comparisons are stronger downwards than upwards.

Last, the income profile over time matters in itself. Those who received higher income or higher income rank in the past supply less effort today, at a given income and income rank. This result is potentially important for understanding for example the frequent failure of mergers. While the literature has concentrated on the role of income, mergers may involve substantial changes in rank as well; we have shown the latter to be a strong determinant of motivation.

There are a number of explanations of the rank-sensitivity of effort. We have presented our results in terms of income comparisons and concern for status. Alternatively, effort choice may derive from inequality-aversion (see for example [START_REF] Fehr | A Theory of Fairness, Competition and Cooperation[END_REF][START_REF] Bolton | Erc: A Theory of Equity, Reciprocity, and Competition[END_REF]: those who receive a high income increase their effort so as to reduce the difference between their own earnings (i.e. income minus effort cost) and those of lower (and particularly the lowest) income workers. While it is difficult to distinguish cleanly between theories, we note that inequality-aversion would predict a stronger effort role for others' incomes than for income rank, whereas in both experimental and survey data we find the opposite. Also inequality-aversion does not explain the role of past income and income rank in explaining current effort, whereas income comparisons do.

Another alternative explanation of the experimental results is that workers learn what the "fair income" is in the group: their effort does not depend on within-period comparisons as such, but by the search for the norm. However, if this were the case, they should reject more offers over time as they learn what the fair income is, and should reject more contracts in the Information Treatment than in the Benchmark Treatment. Neither of these predictions holds. Searching for the fair income also implies that individuals pay attention to both the top and the bottom of the income distribution, whereas for given income and income rank, individuals only care about the gap between their income and lower earnings.

A very general implication of our work is that combining survey analysis, based on subjective data, and experiments in a controlled environment serves as a validation exercise. While both approaches have been criticized for separate reasons, here they produce remarkably similar and consistent results.

Over 20 years ago, Bob Frank (1985) suggested that firms can trade off status and wages. This paper has shown that these two are indeed substitutes in terms of inciting worker effort. Worker effort is lower in face of both absolutely and relatively low incomes, where this relativity concerns both others in the same period and oneself in previous periods. This may explain why firms favor income secrecy, and also why the same income at a point in time might produce different levels of effort. They also demonstrate the concrete advantage accruing to firms paying rising income profiles. More generally, income comparisons, both to others and to oneself in the past, seem to be a pervasive element of economic life.

How are payoffs in each period determined?

The employee's payoff 1. If the employee has rejected his firm's offer, his payoff is zero for the period.

2. If the employee has accepted his firm's offer, the employee receives his income. He must subtract from this income both a transportation cost of 20 points and the cost associated with the quantity of work he has chosen.

3. The employee determines his quantity of work in choosing a number in between .1 and 1, as indicated in the Table below. The smallest quantity of work is .1 and the largest is 1. The higher the number chosen, the greater the quantity of work, and the higher the firm's payoff.

4. The greater the quantity of work chosen, the higher is the associated cost to the employee. The Table below shows how costs vary with the quantity of work.

5. In the case that the income offer is accepted, the employee's payoff in points is determined as follows:

Employee's payoff in points in each period = The employer's payoff 1. At the beginning of each period, the firm receives 120 coupons from the experimenter that can be used to pay the income of the current period. If the firm offers a income of 120 points to his employee and if this offer is accepted, then the firm has no coupons left. If the firm offers a income of 20 points to his employee and if this employee accepts this offer, then he has 100 coupons left. More generally, the firm keeps:

Income -cost of the quantity of work -transportation cost

120 coupons -the income paid to the employee 2. How are the remaining coupons converted into points? The number of coupons kept by the firm is multiplied by the quantity of work chosen by the employee. The result indicates the firm's payoff in points for the current period. Then, Firm's payoff in points in each period = (number of coupons -income) * quantity of work 3. If the employee does not accept his offer, the firm loses its coupons and its payoff is zero for the current period.

At the end of the period, the firm and his employee are informed about their respective payoffs.

At the end of each period, the next starts automatically. The firms and the employees are re-matched randomly to form new pairs.

Throughout the entire session, you are not allowed to talk if not invited to do so. Any violation of this rule will result in being excluded from the session and not receiving payment. If you have any questions regarding these instructions, please raise your hand. Your questions will be answered in private.

--------------------------

  The equilibrium of this game is a minimum wage -minimum effort pair of decisions, [w=20, e=0.1], with selfish and rational players. The minimum wage contract should be accepted since the employee has no better alternative. Equally, the employee should accept the contract and choose the same (minimum) effort level in both treatments since the incomes offered by other firms do not enter into the standard individual utility function. The firms should thus offer the same (minimum) income in both treatments.

  The program paired firms and employees randomly and anonymously. As the game was repeated 10 times under a perfect stranger matching protocol, each firm made an income offer to each of the employees. This leaves us with a total of 200 wage offers in the Benchmark Treatment and 400 wage offers in the Information Treatment. The average income offered is 53.51 (Standard Deviation 19.7) in the Benchmark Treatment and 53.09 (S.D. 20.0) in the Information Treatment. Both are clearly above the equilibrium wage of 20 (one-tailed

  comparisons affect individual behavior in both survey and experimental data. Two different specifications of comparison income are used. The first is in normalized rank form, defined as: rank in cell or group / number of observations in cell or group, with a correction for ties. This measure is bounded between just over zero for the bottom-ranked income in the cell to one for the top-ranked income. The second is average reference group income, excluding the individual's own income. Average and individual earnings levels are expressed in thousands of U.S. dollars per month in the ISSP data, and in experimental currency units in the experimental data. Estimation of effort in the ISSP survey data is via ordered Probit. Estimation of the influence of comparison income on effort in the experimental data is via random effects Tobit.12

  1% I work hard, but not so that it interferes with the rest of my life 38.8% I make a point of doing the best work I can, even if it does sometimes interfere with the rest of my life 48.1% Keeping only full-time or part-time employees aged 16-65 yields a sample of 12 000 observations over 17 countries (considering the two Germanies separately). Missing values on earnings, hours of work and effort produce a regression sample of around 10 000 observations.

		16.7%
	Agree	42.4%
	Neither agree nor disagree	24.2%
	Disagree	12.0%
	Strongly disagree	4.5%
	As a robustness check, we also use a second effort variable. Respondents are asked:

"Which of the following statements best describes your feelings about your job?". The weighted percentages of ISSP respondents who chose each option are shown below:

I only work as hard as I have to 13.

Table 1 .

 1 Mean Discretionary Effort by Country: ISSP 1997.There is something of a country pattern in the degree of social reciprocity at work. Mediterranean countries are broadly towards the bottom of this ranking, while workers in Anglo-Saxon countries are on average more willing to work hard to help their firm or organization. Portugal is an exception to this general rule, appearing towards the top of the ranking.6 The main thrust of our paper is, conditional on country, to see how workers' discretionary effort is related to individual demographic and job characteristics. We are especially interested in the role of income. We control for individual income and hours of

		Employees
	Country	interviewed No. %	Mean Effort
	USA	775	6.47	3.93
	Canada	546	4.55	3.75
	Portugal	843	7.03	3.71
	Switzerland	1 727	14.41	3.65
	Denmark	600	5.01	3.64
	Great Britain	545	4.55	3.63
	Japan	607	5.06	3.62
	Hungary	626	5.22	3.60
	Czech Republic	526	4.39	3.60
	Norway	1 366	11.40	3.59
	East Germany	261	2.18	3.59
	West Germany	648	5.41	3.52
	Sweden	793	6.62	3.42
	Spain	387	3.23	3.35
	Poland	564	4.71	3.26
	Italy	475	3.96	2.96
	France	698	5.82	2.85
	Total	11 987	100.00	3.55

work, but also for reference group income. This latter is defined in a similar way to that in the Leyden school: by calculating average values of income in fairly broad demographic groups, 7 here country, gender, education and age. There are three education groups (10 or fewer years of education, 11 to 13 years education, and over 13 years education), and three age groups (16 to 29, 30 to 44, and 45 to 65). There are thus 17 (country) * 2 (sex) * 3 (education) * 3 (age) = 306 reference groups. These average income measures are called comparison income in the regression tables, and correspond to y* in equation (

4

) above.

8

Comparison income for individual i in cell j is calculated excluding i's own income, which obviates the need to cluster the regressions at the reference group level.

Table 2 .

 2 The cost of effort in the experiment

	Effort e	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1
	Cost c(e)	0	1	2	4	6	8	10	12	15	18

Table 3 .

 3 Average income and effort levels in accepted contracts

	Effort level	.1	.2	.3	.4	.5	.6	.7	.8	.9	1
	Benchmark
	Number obs.	98	22	16	12	11	9	4	5	2	1
	Mean income	50.9	50.1	61.5	64.1	69.7	71.1	71.3	80.0	95.0	60.0
	Information
	Number obs.	214	45	32	29	13	18	13	8	0	6
	Mean income	44.4	59.2	65.4	64.0	69.6	75.6	80.8	79.4	0	93.3

Table 4 .

 4 Effort, Rank and Reference Group Earnings Robust standard errors in parentheses. *** significant at the .01 level; ** at the .05 level; * at the .1 level.

	Variables

Table 4

 4 shows that effort is almost always strongly correlated with own absolute income. This result also holds in the Benchmark Treatment. The same regression of effort in this base treatment, not reported here, has own absolute income positive and significant at the 1% level. Moreover, in the second regression in each panel, normalized

	rank attracts a positive and significant coefficient.	For the same number of
	dollars/experimental units earned, individuals are willing to work harder the higher their
	position in the reference group income distribution. In the experiment, a rise in rank of
	one position increases effort by 0.457 (=0.20*2.285), which is equivalent to a wage
	increase of 4.57 for given rank. Compared to average income per period (53.09), this
	represents a 8.6% rise. The rank/income elasticity is thus 0.43 (=8.6/20). With the ISSP
	data, a 20% rank increase is worth $606 per month, which is 32% of average income,

Table 5 .

 5 Effort: Upwards and Downwards Comparisons

	Note: Robust standard errors in parentheses. *** significant at the .01 level; ** at the .05 level; * at the .1
	level.

Table 6 .

 6 Effort and Past Income in the Experimental Information Treatment

	Variable	(1)	(2)	(3)
	Income	0.116***	0.108***	0.105***
		(0.013)	(0.014)	(0.014)
	Normalized Income Rank	1.865**	2.232**	2.585***
		(0.862)	(0.904)	(0.968)
	Running Minimum Income	-0.002		0.004
		(0.013)		(0.017)
	Running Maximum	-0.045***		-0.013
	Income	(0.012)		(0.017)
	Running Minimum Rank		1.217	-0.148
			(0.755)	(1.166)
	Running Maximum Rank		-2.39**	-2.920**
			(1.25)	(1.504)
	Male	1.182***	-0.717*	0.839**
		(0.452)	(0.371)	(0.407)
	Period 10	-0.249	-0.384	-0.316
		(0.468)	(0.456)	(0.471)
	Experience	-0.564	-1.433***	-0.541
		(0.519)	(0.498)	(0.683)
	Constant	-3.138***	-3.652***	-2.777*
		(1.077)	(1.288)	(1.693)
	Observations	338	338	338
	Log-Likelihood	-364.14	-360.44	-363.37

Note: Standard errors in parentheses; *** statistically significant at the .01 level; ** at the .05 level: * at the .10 level

  Transportation cost = 20 points Relationship between the quantity of work and the associated cost

	Quantity of	.1	.2	.3	.4	.5	.6	.7	.8	.9	1
	work
	Associated	0	1	2	4	6	8	10	12	15	18
	cost

In the rest of the paper, when we evoke income comparisons in the experimental data, we define income as the wage offered by the employer to the employee, i.e. we do not take into account the cost of effort that depends on the level of effort chosen by the employee.

Formally, d 2 U i /da i da j = 0.

Recent contributions in this vein have analyzed saving[START_REF] Duflo | Participation and Investment Decision in a Retirement Plan: The Influence of Colleagues' Choices[END_REF], tax evasion[START_REF] Fortin | Tax Evasion and Social Interactions[END_REF], labor supply[START_REF] Woittiez | Social Interactions and Habit Formation in a Model of Female Labour Supply[END_REF][START_REF] Aronsson | Identifying Interdependent Behavior in an Empirical Model of Labour Supply[END_REF], and students' success at school[START_REF] Arcidiacono | Peer Effects in Medical School[END_REF][START_REF] Sacerdote | Peer Effects with Random Assignment: Results for Dartmouth Roommates[END_REF]).

Most of the experimental work on the impact of others' income tests for inequality aversion and focus on distribution decisions through choices over tax rates, transfers or the distribution of income (see[START_REF] Cowell | Inequality, Welfare and Income Distribution: Experimental Approaches[END_REF].

This cell-average approach does not suffer from the identification problems which occur when y* is predicted in a regression framework, as the cell-average income is not a linear function of the X variables (the variables which define the cells -here country, age, gender and education).

In the Benchmark Treatment, 20 contracts were rejected (respectively 22 contracts in the Information Treatment). We thus obtained 180 effort decisions in the Benchmark Treatment and 378 in the Information Treatment.

Tobit models are used in the experimental data to account for both the right and left-censoring of the effort variable.

If we consider individuals instead of decisions, we observe that only a minority of subjects behave selfishly. Defining as selfish individuals those subjects who choose the minimum effort in at least 8 periods out of 10, we have 35% of selfish people in the Benchmark and 27.5% in the Information Treatment. We cannot however determine whether this difference is inherent to the very nature of the subjects involved in the two treatments or if it is attributable to the dissemination of income information. If the latter, some fraction of minimum effort decisions are motivated by social comparisons rather than selfishness.

The ISSP results are largely unchanged when we drop the 20% of observations which are found in reference groups with 30 observations or less, or if we use a less aggregated reference group by dropping education, or by age.

This result concurs with that in[START_REF] Brown | Does Wage Rank Affect Employees' Wellbeing?[END_REF], where income rank is shown to outperform average reference group income in three satisfaction equations (influence over the job, achievement, and supervisor's respect). For the fourth dependent variable, satisfaction with pay, both rank and reference group income attract significant coefficients.

[START_REF] Kagel | Handbook of Experimental Economics[END_REF] report many examples in which experience (of the game itself or of the same class of games) leads the subjects to play strategies closer to the equilibrium, although not systematically. This is particularly the case in auctions or public goods games. The impact of experience, considered here as learning how to play a particular class of game, has been particularly discussed in the case of voluntary contribution games. In our experiment, nobody had participated to a gift exchange game in the past but may have participated in a public goods game.

These are only calculated for countries where income is measured continuously, rather than in bands (Hungary, Italy, Sweden, Poland and Switzerland).

Data from period 1 are dropped as income (income rank) and running maximum/minimum income (income rank) necessarily coincide in this period.

grateful to R. Zeiliger for programming the experiment presented in this paper, to K. Ben Abbes and M. Bouamoud for assistance in the lab, and to the MiRe -DREES (French Ministry of Social Affairs) for a grant to support this research.

The ISSP data were collected by independent institutions in each country, and documented and made available by the ZENTRALARCHIV FUER EMPIRISCHE SOZIALFORSCHUNG, Köln. Neither the original collector of the dataset nor the Archive bear any responsibility for the analyses or interpretations presented here. We are also

Appendix: Experimental Instructions in the Information treatment

General information

You are going to participate in an experiment on the labor market for the MiRE-Ministry of Social Affairs. If you read these instructions carefully, you can earn a considerable amount of money. The amount of your earnings depends not only on your decisions, but also on the decisions of the other participants you will interact with. During this session, your earnings will be calculated in points, with 100 points = 4 Euros At the end of the session, all the profits you have made in each period will be added up and converted into Euros. In addition, you will receive a show-up fee of 4 Euros. Your earnings will be paid to you in cash in a separate room in order to preserve confidentiality.

At the beginning of the session, each of the 20 participants will be assigned one of two roles: 10 participants will be "employees" and 10 participants will be "firms". Your computer screen will inform you about your role. You will keep the same role throughout the session. You will never be informed of the identity of the participants you will interact with.

The labor market consists of 10 periods.

Decision-making in each period

Each period consists of two stages.

-In the first stage, each firm is paired randomly and anonymously with an employee. Each firm makes a income offer to his employee. The employee is informed of the income offer made by his firm and he is also informed of the income offers made by 4 other firms randomly chosen in the room.

The employee can accept to work for the income offered by his firm or not to accept his firm's offer. If the employee accepts the offer, he proceeds to the second stage.

-In the second stage, the employees who have accepted an offer must decide on their quantity of work.

The details of the procedure are explained below.

Please note that in each new period, the firm-employee pairs are reshuffled. You are sure not to interact more than once with the same firm or with the same employee if you are a firm.

Information about the labor market in each period

1. At the beginning of the period, the firm makes an offer to the employee. This income is between 20 and 120 points. Information about this income offer will be communicated to 4 other employees.

2. The employee is informed about both the income offer made by his firm and the income offers made by 4 other firms to their employees. These firms are chosen randomly.

3. The employee can accept the offer from his firm and work. He can reject the offer and, in this case, he does not work: both he and the firm earn nothing for the current period. Only the firm is informed about the acceptance or the rejection of his offer by his employee.

4. If the employee has accepted the income offer, he receives his income and must decide on his quantity of work. The firm is informed about this quantity of work but neither other firms nor other employees are informed about it. The employee must bear a transportation cost of 20 points.


Elodie Kacioui-Maurin
email: elodie.kacioui-maurin@univ-amu.fr

Jennifer Lazzeri
email: j.lazzeri@yahoo.fr

Valérie Michon
email: valerie.michon@univ-amu.fr

THE STRATEGIC INTENT OF LOGISTIC SERVICE PROVIDERS ON THREE PROCESSES: FRENCH CASE

Keywords: Logistics Service Providers, strategic intent, inductive approach

Purpose: Our aim is to discuss the strategic intent of French Logistic

Introduction

Globalization, lead time reductions, sustainability requirements are some of the reasons explaining that managing supply chains has never been so complex (Hertz andAlfredsson, 2003;[START_REF] Christopher | Logistics and supply chain management[END_REF].Firms refocus on their core businesses and value-adding operations, sooutsourcing to Logistics Service Providers (LSPs) is a part of a general trend. Using their capabilities, LSPs can coordinate the organizations in the supply chain, the activity and flows within the chain, the logistics resources and systems [START_REF] Cui | Networks and capabilities as characteristics of logistics firms[END_REF]. Initially their businesses were centralized on transport but the outsourcing perimeter was extended to warehousing and distribution operations. However, the function of LSPs is focused on the operational coordination among supply chain members. Amongst LSPs, two main categories are distinguished: 3PLs and 4PLs (Hertz andAlfredsson, 2003). The first one has logistics assets and the second one works primarily through information systems, using other 3PLs or carriers as subcontracting firms, since they do not own any assets or very few of them. Over time, LSP's role has evolved, some authors qualify them as leaders (Fulconis andPaché, 2005) others asorchestrators (Zacharia et al., 2011). They are serving as interface actors, being a key player in the supply chain organization.

We use three doctoral researches, with a homogeneous methodology.The first one focus on the innovation in the logistic service providing sector (Kacioui-Maurin, 2011), the second one deals with the total traceability implementation in the food processing sector (Lazzeri, 2014), and the last one concerns the logistic pooling in the distribution sector (Michon, 2014).

These three researches, based on a strategic and logistic managerial way of thinking, are part of an interpretative approach and are based on qualitative methods using in depth case studies. The case study method (Yin, 2003), was chosen for each of these doctoral searches to improve the comprehension of complex in-field studies with multiple analysis levels and to discover new issues. Each of these three in-field studies describes one specific logistic process. The results highlight that LSPs (table 1) have a responsive behavior in relation to their client's requests according to the three observed logistic process (innovation, traceability and logistic pooling). Through a compared analysis, we are willing to identify the factors that can explain the lack of PSLs proactive behavior if we consider the studied process, in the French case. We presentin aninductive approach, in the first part, the chosen logistic process for this analysis and the main raw results. In a second part, we discuss these results, building upon a theoretical proofreading on strategic intent (Hamel and Prahalad, 1989). The LSP, being central in the supply chain, could develop a proactive strategic behavior. This leads to a conclusion based on recommendations to them.

LSPs functions in logistics processes

According to the European Outsourcing Barometer (2008), 68% of firms outsource the transport, logistic and distribution functions.

The LSP needs to be able to act as an intermediate, and to undertakeat the same time some capabilities to solve problems of coordination and to develop adaptive capacities with their clients.

The outsourced logistic activities might be standardized (e.g. transportation, warehousing) or complex (e.g. information system, traceability system and eventually management systems) (Roques and Michrafy, 2003). The proposed activities of LSPs, being controlled, executed and coordinated are on an operational level. This ability to connect, to coordinate and to combine, might take place on a much larger supply chain: LSPs. They can be in charge of managing a large network composed of different actors, activities, and resources, being part of multiple supply chains, among which they will be in the position to create synergies.

We propose to illustrate the complexity and the variety of situations three logistic processes in which the LSP role could be central.

Innovation process

Innovation, in the widest sense of the word, is presented as a main driver for product and service differentiation (Porter, 1982). For firms, innovation'saim is to insure their survival and growth in terms of activities and turnover. Intensive innovation occurred at a high level of competitiveness due to competition and to the high level of uncertainty. Logistics does not escape these problems. As Rossi et al. (2013, p. 587) points out "logistics innovation is often seen as a key driver for enhancing the competitive advantage of a company". LSPs innovation can be considered "as the introduction of a new offer, new technologies on new markets and/or with new shipper which can involve a reorganization of the processes or another significant evolution of the LSPs competencies and services" (Kacioui-Maurin, 2011, p. 133). This process takes on main strategic issues. The concept of "new" and "customer value" are two main dimensions of logistics innovation (Rossi et al., 2013). It appears as the main way of improving LSP performance and profits (Selviaridis and Spring, 2007). As Rossi et al. underlined (2013, p.587) "this implies a firm being proactive by exploring new opportunities for customers that are intended to contribute to the performance and/or effectiveness of the firm".

Existing literature suggests that "modular solutions" appear when the LSP articulates services that have a high degree of complexity and adapts their processes to their customer, such as the management of the after-sales service, the realization of operations of direct marketing, which coexist with more traditional ranges of services, such as the transportation of goods. This extension argues of the evolution of LSPs core business and of their mission in the supply chain. This inevitably, came along with the innovation strategy, proactive or reactive, concerning either the global offer or the processes, the technology supported and being incremental or revolutionary changes (Kacioui-Maurin, 2011).

In a doctoral research, conducted in 2010, LSPs conducted exclusively incremental innovation (Kacioui-Maurin, 2011). According to the framework of Hertz and Alfredsson (2003), LSPs can be considered as standard third party logistic provider, as customer adapter, as service developer, as customer developer. Incremental innovations are much more implemented because of the lower risk they gender. The LSPs'wish of innovation does not apply on all types of services they propose.

According to the type of logistic service, the part of innovation will not be the same both for the LSP and its customers. "When we are with customers on more common services and when we are strangled bythe price level, then there is much less innovation"(Engineering Manager, LSP5).

LSP innovations processes are complex, dynamic and implemented under constraints. They are complex because they combine different innovations by their nature and intensity. They are considered to be dynamicbecause of the permanent evolution of the LSP services and their core business. Thus, it supposes the creation, the mobilization and the capitation of resources and skills (individual or collective). Finally, under constraints, innovation is strongly influenced by characteristics of every LSP but it is especially strongly forced by the characteristics of the relations maintained between the LSP and its customer(s) such as the contract length or the shippers' vision of outsourcing. "The duration of contracts (3 to 4 years) can slow down the investments. And the life expectancy of a customer is 6 to 8 years. Our customers can be more or less mature according to the nature of the market but also according to the type of product. That's the reason why they can be more or less concerned with innovation. The impact of what is around the customers is very important." (Engineering Project Manager, LSP5) These variables can modify the path of innovation of the LSP but more globally that of each actor of the value chain. None of the studying LSPs adopts proactive approach regarding innovation. As strategic they can be, the processes of innovation in logistics services remain processes under constraints.

Traceability processes

Traceability constitutes the functionalities of a tracking and tracing system. "The tracing capability allows, for any product and from any stage within the value chain to identify the initial source (backward tracing) and, eventually, its final destination (forward tracing). The tracking capability allows, to identify for any product, the actual location at any given time. Together, theses capabilities constitute the functionalities of a tracking and tracing system" (Fritz andSchiefer, 2009, p. 317).Though, it is an up-to-date topic, for researchers and managers. Since the mad cow disease or "BSE", it has become a priority for firms. It is now more than two decades since this health crisisbut traceability is still present in the news (e.g. counterfeiting, product recall).

In addition to the quality management, the implementation of traceability presents reputation, marketing, logistics and legal issues (Marucheck et al., 2011). It is a vector for a strategic development for companies (Rabade and Alfaro, 2006;Lazzeri and Fabbe-Costes, 2014). Amajority of authors tend to consider traceability as a mechanism that jeopardizes overall group viability and enhances competitiveness (i.e.competitive advantage, better control of process costs, including logistics).

However, studying traceability across a company is not enough. Most traceability systems are not limited by the border of a unique company but spread (or try to spread) all over the logistics partners involved in the chain. There has been keen interest in successive subcontracting. This has led fragmentation of supply chains and therefore a lack of visibility. These changes usually increase risks of failure. Some authors argue that firms would manage their supply chainneed to work towards a more complete traceability, the so-called « total traceability ». It represents the ability to follow in realtime, throughout the whole supply chain, the physical, informational, financial flows, and the activities and resources (e.g. stock) (Lazzeri, 2014).

A doctoral research was conducted in 2014 in a food chain. We interviewed firms, shippers andLSPs,about their motivations prompting them to display a growing interest in total traceability.They all consider that this is a relevant topic. Practices are also moving in this direction. Moreover, firmshave specific motivations. The research results enhance that the main reasonwhy LSPsdevelop total traceability deals with responsibilities. There is no strategic behavior. This result can be explained by the fact that LSPs are subcontractors. Their mainaim to develop traceability is to be discharged from further responsibilities. The results show that the LSP, who is an intermediate actor, has an important function in the traceability system. Nevertheless, they should consider the potential benefits of the implementation of total traceability as well as being more pro-active in regards to their customers.

Pooling

The logistic poolingcan be described as the process, for a group of shippers, of sharing logistic resources and sharing information in order to create value or at least to reduce logistic costs (Pan, 2010;Michon, 2014). Collaboration is the foundation of this kind of process since shippers agree together to participate in a pool, by sharing transportation or warehousing, and therefore are able to participate in an optimized logistics process [START_REF] Chen | Understanding supply chain management: critical research and a theoretical framework[END_REF]). In the grocery sector, in France, regulation changed in 20081 , forcing retailers to reduce their payment period to their suppliers.Therefore, they decided to reduce their stocks inside their shops and in their own warehousing. Retailers force suppliers to increase their deliveries frequency and to reduce the number of products per delivery, to fit as well as possible their sales, with the final objective of a just in time delivery process. Suppliers do have to organize differently their deliveries to fit these new retailers' requirements. This leads to an increase in logistic costs unless solutions are found to, at least, stabilize these costs. Logistic pooling is a solution since at least two shippers are collaborating to organize their deliveries to their similar clients. In a more optimal way, they organize also the upstream of the supply chain with a common warehousing site. These shippers are moving from a model where they buy a service to a LSP or a carrier, to a model where they need to share information and resources to implement a new logistic process. They create a network, which need to be organized and managed.A real synergy has to be found to optimize the pool: the scheme "suppliers -retailers" has to be tested and implemented. All products don't fit together with the transportation or warehousing requirements and need to belong to the same logistic product family. That makes the meeting point within the retailers quite difficult.

The LSP is legitimate to eventually create, organize and optimize the pool, as one of the supply chain actors and as the intermediate, at the junction of different supply chains. Even if all the LSPs are not able to propose these services since they do not possess the right capabilities to do so (Simatupang and Sridharan, 2002), some of them have either experienced or are actually experiencing this logistic process.

In a doctoral research conducted in 2013, a LSP's manager realized that proposing pooling cases represents "a profound change at a strategic level" (Commercial Manager, LSP8), for shippers and for LSPs themselves. The LSP in charge of a pooling case during 2006-2012, had to recruit a specialist in engineering, with a strong experience in change management, to help the LPS teams to think differently their "job". He considered himself as a "facilitator" (Ex-Supply Chain Manager in charge of a pool-LSP2). This pooling case was the only one they experienced. They stopped proposing this service later onsince the leader in the management team dismissed.

The LSP7 that is in charge of several pooling cases and develops this offer on the French market accumulates knowledge since 2003-2004, when they began with the first one: "that's a complete new job and (LSP7) began a long time ago" (Logistic Director, LSP2). When interviewed, the supply chain manager in charge of pooling cases highlighted the human resource strategic plan they had to elaborate to propose this offer. "We wanted to hire a person (x) with a specific knowledge of VMI. She was working on this in a supplier, now she works for us and helped us develop what we didn't really know" (European Director, LSP7). Also they had to find the right software to optimize this process: "first of all, we began with Excel, trying to find how to do this by ourselves since nothing existed, but then we ask a developer to build a IT tool to become much better. We are still working on it to improve it." (Supply Chain Director, LSP7)

So when LSP7 decided to sell pooling processes, they had in mind to differentiate their service: "We chose to go on and to initiate a new thinking: let's not do what the others are doing." (Supply Chain Director, LSP7) Without this in mind this LSP would not have such a success in its pooling cases, being aware that each of the pooling case they work on, are not always getting to the operational point.

Discussion

We suggest to mobilize strategic management works and moreover the ones about strategic intent (Hamel and Prahalad, 1989) to show LSPs challenge.Strategic intent enables a "sense of direction", it's a guide to strategic thinking. The aim is to make new industry competition rules and change the game in ways tohandicap competitors (e.g. new rules for market entry).Implementing strategic intent requires capabilities and resources to meet and win corporate challenges.As we observed earlier, at the operational level, LSPs control, execute and conduct complex activities, but are deprived of a strategic intent on a long-term basis for their present and future operations. They still remain under constraint, even if some of them are strategic. The theoretical framing helps us formulate propositions and build a research framework (figure 1), to confront then to the field. We define the LSPs strategic intent (proposition 1), explain their strategic behavior (proposition 2) and finally identify the factors driving the LSPs strategic intent (proposition 3).

Figure 1: Research framework of LSP's strategic intent

Strategic intent

The three studied process in these doctoral researches highlight the lack of LSPs strategic behavior.

In the innovation process, in the traceability frame or in a logistic pooling scheme, shippers and/or distributors constraints are quite heavy at each stage of their action. LSPs know and control their historical core business and they apply it, without being in an anticipation consideration. While it was possible, for example, to foresee a strategic intent in the LSP behavior in the implementation of a pooling case, the real reason why this choice was made was only motivated by a leader, what can be called a "champion". However, according to Hamel and Prahalad (1989), the strategic intent is federative and has a unifying influence [START_REF] Bartlett | Changing the Role of Top Management: Beyond Strategy to Purpose[END_REF] for a common goal, with a proactive behavior of the organization as a whole.

Proposition 1: the strategic intent is characterized by an active management process that includes a federative and common goal and a pro-active behavior of the LSP.

Strategic behavior

The strategic intent matches with a long-term ambition. It is a change driver and helps to transform the environment, modifying some competition rules (Hamel and Prahalad, 1994). Developing a strategic intent in each of these three processes might be a good way to make a move toward value creation.

Proposition 2: LSPs' strategic intent leads to a long-lasting transformation of its environment.

Firms, with a strategic intent will to manage their supply chain, develop a total traceability. Competition is based on anticipation capability, on the process adaptability, and on execution speed. The global vision of the supply chain of the flows, of the activities, and of resources, might help LSPs to decide which partners they can mobilize. LSPs, in trying to capture their clients' needs, can propose not only standardized goods and services, but also high quality products, target and customized products, renewing their offer regularly.

The main objective is to differentiate their logistics service against their competitors and to adopt a lasting competitive strategy. Proposition 2.1:the LSPs' strategic intenthelps to offer distinctive and customized logistics services.

LSPs could anticipate future needs, thanks to data monitoring. For example, business intelligence offers the possibility to anticipate major commercial events (promotion, new product introduction, etc.…) forecasted by the shippers. Proposition 2.2: LSP's strategic intent helps anticipation thanks to business intelligence.

Developing a strategic intent fosters logistics efficiency beyond the operational framework. A strategy linked to anuniformization and a flow optimization (transportation and warehousing) allows proposing to their clients, new services. The logistic effectiveness accompanies conquest of new markets. Proposition 2.3: LSPs strategic intent allows for development and growth thanks to logistic efficiency.

LSPs might be considered as a preferential partner, and with a special engagement at the top level of strategic decisions as they tend to get a strategic intent with a proactive behavior. If not, as we have noticed, LSPs work under the shippers' constraints.

Factors driving LSPs' strategic intent

LSPs' jobs and missions can take variety of processes and activitiespartly co-built and/or co-produced with the supply chain partners in which the LSP is integrated. As a result, the supply chain structure will influence their strategic intent.

Proposition 3:Intra and inter organizational factors influence the LSPs' strategic intent.

Shippers are mainly the supply chain pilots in the studied process. The financial issue of stocks in the process case of total traceability gives to the shippers a power on the nature of the LSPs' business relationship they carry on. Furthermore, the use by shippers of many logistic service providers to avoid the LSPs' rootednessprevents the LSPs' strategic ambitions. Ultimately, the use of outsourcing of logistics activities can limit the LSPs' global vision. Proposition 3.1: the supply chain structure influence the LSPs' strategic intent.

The inter-organisational relations, and their state between the LSP and its client(s) and its supplier(s) can be considered as an obstacle to develop strategic process in the process we studied. The trust between partners, the prior relationship, the frequency and nature of their exchanges(relational or purely contractual) might be considered as influencing these relationships. In the case of innovation process, the contract lengths do not allow the LSPs to develop revolutionary innovations. Proposition 3.2: the inter-organisational relationships influence the LSPs' strategic intent.

We notice, in the studied process, the importance of developing capabilities to propose new services, acquire new technologies, or structure strategic processes. In the case of logistic pooling, interviews of LSPs showed mainly an expertise in these classical offers, and a quite surprising passive behavior to observe what the main 3PL in logistic pooling cases management is doing. Even if some LSPs are describing in professional magazines an experience they have in pooling, on their web site pooling does not appear as a specific offer, as reverse logistic does. It would be convenient to develop organizational competencies and create a leverage effect on resources. Proposition 3.3: LSP's resources and competences influence their strategic intent.

Conclusion

We provide empirical elements to understand the LSPs' behavior. We limit the enthusiastic theoretical way of thinking of LSP's proactivebehavior in the supply chain. The findings offer a research framework. The next stage is to carry out a specific study about the strategic intent of LSPs, their strategic behavior and the driving factors. Apart from the theoretical implications for academics in better scoping future research, the framework presented here should be of relevance to practitioners envisaging the possible weight they could gain in havinga strategic intent.

Despite its contributions, this paper has limitations. First, study is focused on theFrench market, we need to enlarge the perimeter on LSPs corporate strategy. Then, the study is built upon three doctoral searches based on specific logistic processes. It would be interesting to build research design for this issue and include more logistics processes such as reverselogistic processes.

Finally, it would be relevantto interview shippers to analyze the inter-organisational relationships in depth and their impact on LSPs' strategic intent.

Table 1 .

 1 LSPs respondents

	LSP	2013 3PL Logistic sales in France (Millions €)	Typologies of services and clients
	LSP1	670	All sectors
	LSP2	625	Distributors, FMCG (fast-moving consumer goods
			companies), PGC, industries
	LSP3	562	Distributors
	LSP4	950 (worldwide)	Craft stores, furniture, textiles andleisure
	LSP5	486	Distributors, food and beverages, chemical,
			automotive and transport equipment
	LSP6	465	Positive and negative cold, food processing,
			distribution
	LSP7	312	Food processing, industries, retail
	LSP8	273,8	Retail, high tech and electronics, industries
	LSP9	61	Temperature controlled food processing
	LSP10	10,7	Specialized distribution, pharmacy and health care,
			high tech and electronics

  "I can say that I am an efficient LSP, I can trace the driver and say he arrived on time there, so I have proof. That's why we adopt and acquire technology, it's to improve total traceability"(Logistic Manager, LSP1). As highlighted by the Director of the Agency of a carrier, technology development with pictures can help manage litigation and claims, on receipt of goods. "Supermarketscringe with these systems. They cannot tell us, "you were late, you did not come." It allows us to manage customer complaints more quickly "(Logistics Director, LSP1). Traceability variable appears,as a basic service proposed by the LSP, which ensure not to alter the operational information available on physical flows in order to transmit the report to customer demand. "When loading containers of products that travel by boat, usually it's sealed. But not systematically. It depends on the customer demand. We are truly provider. We do what we are asked to "(Logistics Manager LSP6).

Law of Modernization of the Economy -August 4th

-n°2008-776.

 Fritz, M., Schiefer, G. (2009),"Tracking, Tracing, and Business Process Interests in Food Commodities: A multi-level decision complexity", International Journal of Production Economics, Vol. 117, n° 2, pp.317-329.  Fulconis, F.,Paché, G. (2005), "Piloter des entreprises virtuelles", Revue francaise de gestion , Vol. 3, n°156, pp.167-186.  Hamel, G.,Prahalad, CK. (1989), "Strategic Intent", Harvard Business Review, Vol. 67, n° 3, pp.63-76.  Hamel, G.,Prahalad, CK. (1994)