Christiana Maria Nöstlinger

Sibylle Nideröst

Rebecca Woo

Jasna Loos

Tom Platteau

Robert Colebunders

AIDS Impact special issue 2009: Mirror, Mirror on the Wall: The Face of HIV+ Women in Europe Today

Keywords: HIV, women, sexual and reproductive health, prevention, condom use

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

.12, p<.05) and having an HIV-positive partner (β= -.13, p<.05). For study population, consistent condom use performed a challenge. Selected SRH-issues predicted condom use. Sexual risk reduction and positive prevention should be discussed in the context of family planning and integrate SRH perspectives in routine HIV care.

Introduction

When AIDS reached public awareness in the early 1980s, it was viewed as a disease of homosexual men and as a sentence of imminent death. An early study by the US Centers for Disease Control and Prevention (CDC, 1982) quoted a one year mortality rate of 60%. For those with access to highly active antiretroviral treatment (HAART) and care, HIV has now become a chronic illness. More recently, the 5 year risk of death from HIV was noted to be less than 5% (ART Cohort Collaboration, 2007). In 2007, the epidemic was estimated to have spread to some 33 million people (Joint United Nations Programme on HIV/AIDS [UNAIDS], 2008), with about 50% of cases affecting women in their reproductive ages, a proportion which continues to rise. In the WHO European region, a third (33%) of new HIV cases in 2007 was reported among women (European Centre for Disease Prevention and Control [ECDC], 2008).

With these shifts in the HIV epidemic, the focus of care has evolved towards improving the quality of life. Regardless of HIV, sexual expression and experience of parenthood are central issues for the quality of life of both women and men, but people living with HIV (PLHIV) have specific needs in this respect [START_REF] Bharat | Meeting the Sexual and Reproductive Health Needs of People Living with HIV: Challenges for Health care Providers[END_REF][START_REF] Boonstra | Meeting the Sexual and reproductive health needs of people living European Centre for Disease Prevention and Control/WHO Regional Office for Europe[END_REF]. Many HIV positive women of reproductive age today have only been cognizant of their serostatus in the era of HAART, where mother to child transmission rates of HIV are less than 2% (Volmink, Siegfried, Van der Merwe & Brocklehurst, 2007). Access to HAART is seen as a chance to obtain what they once thought was lost: the opportunity to have meaningful sexual relationships and bear healthy children. While SRH presents a basic human right [START_REF] Gruskin | Ensuring Sexual and Reproductive Health for People Living with HIV: An overview of Key Human Rights, Policy and Health System Issues[END_REF]Segurado & Pavia, 2007;[START_REF] London | Even if you're positive, you still have rights because you are a person': Human Rights and the Reproductive Choice of HIV-positive Persons[END_REF], fulfilling SRH-related needs may pose number of challenges: PLHIV and service providers (SP) perceive it as difficult to address sexuality in routine service provision (Nöstlinger et al., 2008).

Enabling comprehensive HIV services to better meet the sexual and reproductive health (SRH)-related needs of their clients will not only contribute to increasing quality of life, but also to onwards HIV prevention.

Objectives

This European cross-sectional multi-centre study aimed at assessing SRH-related aspirations and needs of PLHIV. In this paper, we present specific results pertaining to HIV positive women. We assessed three areas of SRH in more detail (sexual health, motherhood and contraception) and investigated the contributing role of SRH-related issues to sexual protection behaviour, i.e. condom use in steady relationships.

Methods

Procedures

The research was carried out in the framework of a European Public Health Project and research network (Eurosupport 5) consisting of 17 HIV treatment sites, community-based and research organizations in 14 European countries (see figure 1). We adopted a two phase multi-method research design combining qualitative and quantitative methods. In the first formative research phase, SRH-related aspirations and needs were investigated in detail using focus group discussions (FGD) with PLHIV.

FGDs were conducted according to the state-of-the art [START_REF] Morgan | The focus group tool kit[END_REF], details on the procedures reported elsewhere (Nöstlinger et al., 2008). We used purposive sampling to recruit FGD participants until saturation of data was achieved.

These results informed the cross-sectional quantitative study, by adding HIV-specific the information-motivation-behavioural skills model ([IMB]; [START_REF] Fisher | A General Social Psychological Model for Changing AIDS Risk Behavior[END_REF].

Data on the modified IMB constructs were obtained through an anonymous selfadministered questionnaire (SAQU) focusing on demographics, health-and SRH-related variables and condom use (prior 6 months). The SAQU was piloted for feasibility with a small sample of PLHIV. Eligibility criteria were: being able to read, comprehend and answer to the survey independently, understand the study goals and objectives, and being diagnosed HIV positive for at least 6 months.

Insert figure 1 here

Informed consent procedures were carried out at all study sites and ethical approval

Measures

We assessed satisfaction with sexuality through an 11-item scale ranging form '0' (= 'not at all satisfied') to '10' (= 'completely satisfied'). Changes in sexual behaviour were measured by a multiple answer question regarding different kind of changes (see table 1). The variable 'number of changes in sexual behaviour' was established by summing up these answers. This yielded an interval scaled variable ranging from '0' (='no changes') to '5' (='many changes'). Other SRH-related variables were measured directly as dichotomous variables ('yes'/'no'). The dependent variable condom use was expressed as the proportion of condom use at all sexual encounters with steady

Data analysis

Systematic contextual data analysis was used to process qualitative data. Descriptive statistical analyses using the statistical package for social science (SPSS)16.0 were carried out employing frequency analysis. Results were described by central tendency, dispersion (mean, SD) and absolute and relative distribution, where appropriate.

Bivariate correlations and a hierarchical regression analysis were performed [START_REF] Backhaus | Multivariate Analysemethoden. Eine anwendungsorientierte Einführung[END_REF] to test the associations respectively the effect of SRH-related variables. We controlled for the effect of education, migration background, age, undetectable viral load, and having a seroconcordant steady partner. Due to low numbers of women with casual sexual partners, only women with a steady sexual partner in the prior 6 months were included in the bi-and multivariate analysis.

Results

Sociodemographics

In the qualitative study, 43 heterosexual women from 9 FGDs were included in the analysis, in the quantitative study the number of participating women was 387.

Female FGD-participants were on average 39 years old, had lived longer with HIV than 6 years. Thirty-six women (85%) were taking HAART. Nine women were migrants (21%), and more than half lived in a steady relationship.

In the quantitative study, the women's median age was also 39 years (ranging from 17 to 69 years), with the majority in their childbearing years (317/82%), defined as ages 15-45. About a quarter had a migrant background (87/22.5%). The vast majority selfidentified as heterosexual (326/91%). Two thirds reported living in a family setting (253/65%), 102 (26%) lived alone. Women were highly educated, 282 (73%) had completed secondary or higher education, and 192 (50%) were employed.

Health status and HIV-related characteristics

In the quantitative study, the median duration of HIV infection was 8 years. Women became aware of HIV infection at the median age of 29 years; 12 (3%) young women were infected through mother-to-child transmission. The most common way of infection was heterosexual transmission (208/54%), followed by the categories 'unknown' (65/17%), intravenous drug use (IVDU; 44/14.5%) and IVDU plus sexual transmission (28/7%). About one-fourth (103/27%) reported to suffer from HIV-related health symptoms. While 310 (80%) where on ART, 236 (76%) had an undetectable viral load. The mean reported CD4 count was 500 cells/µl.

Sexual health and condom use

The FGD showed that the fear to transmit HIV to their partners was a commonly shared experience among many women. Some women reported being sexually abstinent either due to not having a partner or due to the fear to transmit HIV.

However, almost all sexually active women felt that adhering to safer sex standards on a day to day basis was a major challenge. sometimes…so once in a while, we take chances and we decide to make love without…(female FGD participant with a seronegative partner, Belgium).

While some women spoke about their limited ability to negotiate safer sex issues with their male partners, others perceived unprotected sex as an expression of intimacy in the sexual relationship. Many reported their own risk-benefit analyses depending on the partner's serostatus and sexual practices, thus not always adhering to service providers' strict safer sex messages, which often were perceived as not differentiating between partners' serostatus.

Quote:

"I think that he wants me to be as close to him as possible, to overcome all boundaries between us and somehow condoms symbolise this. He acts as if he wouldn't mind to become infected … that would finally allow us to feel the same thing…" (female FGD participant with a seronegative partner, Poland).

insert table 1 here!

Table 1 shows that the majority of all women participating in the quantitative study were sexually active: 240 (62%) women reported at least one sexual encounter (vaginal/anal intercourse) with their steady partner. One hundred and sixteen (51%) always used condoms on these occasions. Forty-one (11%) were treated for an STI in the prior 6 months, and 25 (6%) had tested positive for syphilis.

HIV diagnosis meant a change in sexual behaviour for many women: 321 (83%) reported to have changed their sexual behaviour in one or more ways, e.g. by using condoms more stringently, choosing monogamy or avoiding 'risky' sexual practices. Nevertheless, the satisfaction with sexuality was quite high (M=6.7, SD= 2.50).

Motherhood and HIV

Qualitative results showed that for many women pleasure and happiness were tied to parenting. Some women had decided not to have children because of service providers' advice or fear to infect the child. In the light of available treatment options, some women still struggled with that decision. Others had opted for children, but questions on the potential impact of the pregnancy on HIV remained. For most women, the crucial question focused on how to conceive safely.

Quote:

"Some people around me say it's quite selfish to desire another child. I do have one healthy child already out of my previous marriage, so why take chances? Quantitative results (see Table 2) show that the majority (221/57%) had children, and 135 (35%) had become pregnant since their HIV diagnosis. In addition, many (157/41%) wished to have more children. A further 10% (40 women) had suffered from a miscarriage. Fifty-three women (14%) had terminated a pregnancy since their HIV

Contraception

In the FGDs women expressed a high need for safe contraception: while many women used condoms as primary method, many were concerned about their contraceptive efficacy. A uniform result across all FGDs was that women missed routine delivery of family planning information and advice. Women often felt left alone in the decisionmaking on the most suitable contraceptive method. In addition, misconceptions were highly persistent in some sub-groups, such as African migrant women.

Quote:

"I am afraid of using the pill, it affects a woman's health so that she never will be able to have babies again, she'll become infertile or have a miscarriage…" (FGD participant, Sub-Saharan African migrant, UK).

The questionnaire data showed that 214 (55%) used some form of contraception (156/40% used only a condom, 45/12% condoms in combination with other methods).

SRH-related variables as predictors of condom use with steady partner

Table 3 shows the correlation matrix for the SRH-related variables and condom use for the 240 women who had sex with a steady partner during the past 6 months prior to the study. Significant associations were identified between condom use and the use of ). The proportion of explained variance of these variables was 23%.

insert table 3 and 4 here

Discussion

Our data shows that consistent condom-use with steady partners presented a major challenge to sexually active many women living with HIV. Selected SRH-issues and seroconcordance predicted condom-use in this group.

We should note some limitations of this cross-sectional study conducted among a convenience sample of HIV positive women. Respondents had volunteered to participate on an anonymous basis. Therefore selection and social desirability bias apply, as to many other studies using self-reported data. These factors may limit the application of our findings to HIV positive women in general. Notwithstanding these methodological limitations, and given the additional explanatory insights from the qualitative assessment, our study reveals some significant findings relating to the SRH needs of HIV positive women. The majority of women were sexually active, but had completed their childbearing. Women reported the conspicuous absence of integrated contraceptive counselling, and the rate of pregnancy termination (almost half of all pregnancies after HIV diagnosis) underscored this failure of service provision. While all the available reversible contraceptive methods can generally be used by HIV-infected women [START_REF] Heikinheimo | Contraception and HIV infection in women[END_REF]World Health Organization [WHO] 2004), women clearly need more information and support on family planning.

In addition, a substantial proportion of women (10%) experienced pregnancy loss. A recent study has highlighted that women living with HIV may be at a higher risk of experiencing pregnancy loss than the estimated 2% of the general population [START_REF] Anderson | Pregnancy loss in HIV-positive women attending antenatal care at a London centre[END_REF]. Cumulative immune suppression and vaginal infections may play a role in this; therefore, careful sexual health screening should be performed as early as possible in pregnancy, as recommended by current guidelines: e.g. British HIV Association and Children's HIV Association [BHIVA] guidance (de Ruiter et al., 2008) to avoid such potentially avoidable losses.

Using condoms consistently was a major challenge for the majority of women included in this study. Although partner-related aspects (i.e. partners' HIV status) were a predictor of condom use, selected SRH-related issues predicted condom use stronger.

The experience of a previous miscarriage was significantly negatively related to condom use: this may suggest that women who miscarried continued to realize their child desire. Women using other forms of contraception were also more likely to use condoms with their steady partners. For them, condoms represent both a contraceptive and sexual health protection. Having an HIV positive partner made one less likely to use condoms. From the qualitative results one may conclude that couples living with HIV established their own risk benefit analysis of sexual risk taking. In such analyses reproductive desires may outweigh potential risks of super-infection.

Our study results are in line with current research on similar topics. However, most of research addressed single target behaviours such as sexual risk taking or fertilityrelated desires, and not how comprehensive SRH-related aspirations may be intertwined with protection behaviour.

In general, studies on reproductive choices among HIV positive women showed that their reproductive patterns were similar to HIV-negative women (Stanwood, Cohn, Heiser & Pugliese 2007), and this includes both planning for having children and preventing unwanted pregnancies. A European study suggested that being HIV-infected neither influenced the desire for children, nor the decision to become pregnant [START_REF] Fiore | Reproductive experience of HIV-infected living in Europe[END_REF], which has been corroborated by our qualitative findings. It has been shown that a variety of biomedical, individual, and socio-cultural factors influence pregnancy decision-making for HIV-positive women [START_REF] Kirshenbaum | Throwing the dice": pregnancy decision making among HIV positive women in four U.S. cities[END_REF], availability of treatment certainly plays an important role (Cooper et al., 2009). Data from the Swiss HIV Cohort study (Panozzo, Battegay, Friedl, Vernazza & the Swiss HIV Cohort Study, 2003) showed that 45 % of female patients expressed a desire for children. In a representative French sample of women and men living with HIV, 33% of the women and 20% of the men expected to have children in the future (Heard, Sitta, Lert & the VESPA study group, 2007). Already having children may influence child desire to some extent: in a previous study carried out by the Eurosupport network among mothers living with HIV, we found that 16% of the women wished to have another child, and 17% were still undecided [START_REF] Nöstlinger | Children and adolescents living with HIV positive parents: Emotional and behavioural problems[END_REF].

The evidence on extent and type of contraceptives used by HIV positive women is still limited (Delvaux & Nöstlinger, 2007). While according to WHO's Medical Eligibility Criteria for contraceptive use (WHO, 2004), most contraceptives are considered safe and effective for HIV positive women, though current supplies of contraceptives including females condoms to women is highly inadequate [START_REF] Foss | Are people using condoms? Current evidence from sub-Saharan Africa and Asia and the implications for microbicides[END_REF]. In spite of the currently available treatment options, an HIV positive diagnosis may have a tremendous impact on a woman's decision to carry a pregnancy to term. Several studies assessed the rate of induced abortion among HIV positive women in industrialised countries. Before the introduction of HAART these rates were around 63% [START_REF] Bongain | Changing trends in pregnancy outcome among HIV-infected women between 1985 and 1997 in two southern French university hospitals[END_REF]. The availability of treatment may have altered this picture reducing the number of pregnancy termination while at the same time the number of births increased (van Benthem et al., 2000). With regards to sexual risk taking, we found a higher rate of sexual risk taking than similar studies: the French VESPA study reported that 34% of the women surveyed had unprotected sex with their steady partners in the prior 12 months (Bouhnik et al., 2007). In another French study 24% of the heterosexual women reported occasions of unsafe sex (Peretti-Watel et al., 2006). In this study, being unaware of partners' serostatus was a reason for sexual risk taking, next to a history of drug use, and a difficult financial situation.

Conclusions

As with all studies addressing sexuality, we address a behaviour that is highly sensitive, partly unconscious, and irrational. HIV adds the notion of stigma, rendering service delivery and counselling even more challenging. As a consequence, women living with HIV in our study had numerous unmet SRH needs: inadequate contraception and family planning, and challenges regarding consistent condom use. Therefore, HIVproviders must be willing and trained to discuss SRH topics in a gender-specific and culturally sensitive way despite time and language constraints. Condoms should not only be discussed as an HIV prevention method, but also in the context of available contraception and family planning for positive women. While our study highlights SRH aspirations and behaviours as well as their potentially influencing factors, there is need to translate these findings into program planning and implementation, such as evidence-based guidelines for positive prevention counselling, effective strategies to Center for Disease Control (1982). Current Trends Update on Acquired Immunedeficiency Syndrome, -AIDS, United States. MMWR, 31(37), 507-508, 513-514. Cooper, D., Moodley, J., Zweigenthal, V., Bekker, L.G., Shah, I., & Myer, L. (2009).

Fertility intentions and reproductive health care needs of people living with HIV in Cape Town, South Africa: implications for reproductive health and HIV care services. & Behavior, 13(Suppl.1), 38-46. Delvaux, T., & Nöstlinger, C. (2007). Reproductive Choices for Women and Men Living with HIV: Contraception, Abortion and Fertility. Reproductive Health Matters, 15(Suppl.29), 46-66. de Ruiter, A., Mercey, D., Anderson, J., Chakraborty, R., Clayden, P., Foster, G., & Gilling-Smith, C. (2008). British HIV Association and Children's HIV Association guidelines for the management of HIV infection in pregnant women 2008. HIV Medicine, 9(7), 452-502. 1234AIDSIMPACT SPECIAL ISSUE: Mirror, Mirror on the Wall: The Face of HIV+ Women in Europe Today

AIDS

  were established: the use of contraceptives (β= .33, p<.001), miscarriage since HIV-diagnosis (β= -.16, p<.01), childbearing since HIV-diagnosis (β= -

  partners' HIV-status, knowledge and attitudes relating to positive prevention, HIV-disclosure etc. to the theoretical model that guided our research, i.e.

  was obtained at the coordinating site (Institute of Tropical Medicine/University of Antwerp). Qualitative data were collected between 12/2005 -06/2006, and quantitative data between 03/2007 and 04/2008.

  s really challenging, you know, like you know that you should be using condoms for the rest of your life, all the time, … me: I'd just wish I could forget about it, at least

  But I 'd wish to become pregnant again and have a second baby…my partner is also HIV positive and we are both undetectable. I wonder what the chances really are to harm the baby..." (FGD participant, Belgium).

  contraceptives, childbearing since HIV-diagnosis, miscarriage since HIV-diagnosis and the changes made in sexual behaviour after HIV-diagnosis. The hierarchical regression analysis established that the use of contraceptives increased condom use with steady partner, whereas having given birth to a child and having suffered from a miscarriage since HIV-diagnosis decreased the condom-use. In addition, being in a steady HIV-positive partner reduced condom use (see table 4

  for couples of both same and different HIV status. An overall integration of SRH and HIV issues should be offered in standard service provision. Guttmacher Policy Brief, nr. 6. The Guttmacher Institute, Accessed at: http://www.guttmacher.org/pubs/IB_HIV.html. Bouhnik, A.D., Préau, M., Schiltz, M., Lert, F., Obadia, Y., Spire, B., & the VESPA study group (2007): Unprotected sex in regular partnerships among homosexual men living with HIV: a comparison between sero-nonconcordant and seroconcordant couples (ANRS-EN12-VESPA Study). AIDS, 21(S43-S48). doi: 10.1097/01.aids.0000255084.69846.97

  ., Gordillo, V., Borms, R., Murphy, C., Bogner, J.R., Csépe, P.,Colebunders, R., & the EUROSUPPORT Study Group (2008). Differences in Perceptions on Sexual and Reproductive Health between Health Care Providers and People Living with HIV: A Qualitative Elicitation Study. Psychology, Health & Medicine, 13, 516-528. Panozzo, L., Battegay, M., Friedl, A., Vernazza, P. & The Swiss HIV Cohort Study (2003). High risk behaviour and fertility desires among heterosexual HIV-positive patients with a serodiscordant partner -two challenging issues. Swiss Medical Weekly, 133, 124-127. Peretti-Watel, P., Spire, B., Schiltz, M.A., Bouhnik, A.D., Heard, I., Lert, F., Obadia, Y., & the VESPA group (2006). Vulnerability, unsafe sex and adherence to HAART: Evidence from a large sample of French HIV/AIDS outpatients. Social Science and Medicine, 62, 2420-2433. Stanwood, N.L., Cohn, S.E., Heiser, J.R., & Pugliese, M. (2007). Contraception and fertility plans in a cohort of HIV positive women in care. Contraception, 75(4), 294-298. Segurado, A.C., & Pavia, V. (2007). Rights of HIV positive people to sexual and reproductive health: parenthood. Reproductive HealthMatters, 15(Suppl.29),[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]

  Figure 1 -Tables1-4

Figure 1 :

 1 Figure 1: Participating countries (valid self-administered questionnaires)

Table 1 :

 1 Reproductive and Sexual Health Variables (N=387)

	Variable

Table 2 :

 2 Sexual Behaviour and Condom Use Past Six Months (N=387)

	Variable

Table 3 :

 3 Intercorrelations between SRH-Variables and Condom Use with Steady Partner

	Variables	1	2	3	4	5	6	7	8	9
	1 Condom use with steady partner	-
	2 Use of contraceptives	.47 **	-
	3 Childbearing since HIV diagnosis	-.21 **	-.03	-
	4 Miscarriage since HIV diagnosis	-.24 **	-.07	.25 **	-
	5 Abortion since HIV diagnosis	.02	.11	.16 **	.19 **	-
	6 Having children/motherhood	-.05	-.03 *	.54 **	.05	.06	-
	7 Child wish	.09	-.08	.00	-.03	-.02	.27 **	-
	8 Satisfaction with sexuality	.03	-.10	-.01	-06	.07	-.16 *	.01	-
	9 Changes in sexual behaviour	.20 **	.19 **	.04	.02	.01	.03	.06	.12	-
	Note. N=240, *p<.05; **p<.01; ***p<.001

Table 4 :

 4 Summary of Hierarchical Regression Analysis for SRH-variables predicting Condom Use with Steady Partner in HIV-positive Women Note. N= 240, R 2 = 0.07 for Step 1; ∆R 2 = 0.16 for Step 2 (p <.001) *p<.05; **p<.01; ***p<.001

	Variable

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Acknowledgements

We are grateful to all study participants for contributing to this study and to the investigators at the participating centres: Austria: Birgit Mumelter (University of Innsbruck), Gabriele Schmied (European Centre, Vienna); Belgium: Ruth Borm, Koen Block (Sensoa, Antwerp); Lut Lynen, Eric Florence (Institute of Tropical Medicine, Antwerp); Czech Republic: Ivo Prochazka (University of Prague); Germany: Johannes Bogner, Matthias Müller (Ludwig Maximilians University, Munich), Werner Becker, Ramona Volkert (Private Practice, Munich), Andreas Niedermeier (University Clinic for Dermatology, Munich), Martin Karwat (Private Practice, Munich); Greece: Nikos Dedes (Synthesis, Athens); Hungary: Peter Csépe (Semmelweis University, Budapest); Italy: Gloriana Bartoli, Carlo Giaquinto (University of Padua, Padua); Caterina Uberti-Foppa, Giulia Gallotta (HSR Ospedale, Milan); Latvia: Anda Vaisla (Latvian Family Planning Association, Riga); Poland: Michal Pozdal, Zbigniew Izdebski (University of Zielona Góra); Portugal: Luis Caldeira (Hospital Santa Maria, Lisbon); Slovak Republic: Danica Stanekova (Slovak Medical University); Spain: Victoria Gordillo (University Complutense of Madrid); Switzerland: Daniel Gredig (University of Applied Sciences of North-Western Switzerland); United Kingdom: Ed Wilkins and Cinthia Murphy (Pennine Acute Hospitals NHS Trust, Manchester). Our thanks go also to the Swiss National Science Foundation and the Swiss HIV Cohort Study for funding, support and co-operation.

EC disclaimer

This study received funding from the European Commission (SANCO/Public Health), Grant Agreement nr. 2004314. The European Commission is not responsible for any use that may be made of the information contained herein.


Sangho Kim

Rainer Klump
email: klump@wiwi.uni-frankfurt.de

The Effects of Public Pensions on Private Wealth: Evidence on the German Savings Puzzle

Keywords: C23 -Models Life-cycle model, Ricardian equivalence, pension systems, panel estimations, Germany JEL Classification: C23, D91, H55, O52, Life-cycle model, Ricardian equivalence, pension systems, panel estimations, Germany

Based on German panel data between 1984 and 1999 we test for the interaction of social security benefits and private wealth formation. In a simple life-cylce model benefits from public pension systems should displace equal amounts of private retirement accumulation. Our estimate for the offset effect, corrected for several possible measurement biases, is much lower, however, than expected from pure life-cycle considerations and less than comparable estimates for the US and the UK. This result thus supports other evidence on a particular German savings puzzle which might be due to market imperfections and/or bounded rational behavior.

Introduction

By providing a safe income after retirement from active work, social security systems have contributed substantially to the reduction of poverty among the elderly in developed countries. The long-term costs of these social benefits are, however, less obvious and are not yet fully understood. They arise from various effects of social security systems on labour markets and private capital formation leading to possible reductions in future growth and real wealth. While the analysis of possible labour markets effects of the existing pay-as-you-go systems of oldage social security has boomed over the last two decades, the possible capital market and real wealth effects are still less well known. We will underline in this paper the existence and significance of the latter effects. They should be taken into account, when reforms of the existing social security systems are being discussed.

The pioneering study by [START_REF] Feldstein | Social security induced retirement and aggregate capital accumulation[END_REF] sparked the debate on whether or not transfer-based social security retirement benefits influence the saving behaviour of individuals. Following Ricardian equivalence theory as put forward by [START_REF] Barro | Are government bonds net wealth? Journal of Political Economy[END_REF], there is no reason to expect any substitution in household wealth formation if the retirement transfers are financed by (lump sum) social security taxes. Other studies focusing on the life-cycle model of individual decisionmaking (e.g., [START_REF] Feldstein | Social security and household wealth accumulation: new microeconomic evidence[END_REF][START_REF] Bernheim | The economic effects of social security: toward a reconciliation of theory and measurement[END_REF]) came to the result that public old-age security can completely offset private household saving.

Empirical investigations that so far have tested the existence and the magnitude of such offset effects had to overcome serious measurement problems and provided rather mixed results.

Our study contributes to this debate by focusing on evidence from Germany where the public pension system has a long history going back to the end of the 19 th century, but has also experienced a series of institutional shocks due to the two world wars, deep economic crises and the division of the country. Following [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF][START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] we try to capture several measurement biases that can veil the true interaction between social security benefits and private capital formation.

Based on German panel data between 1984 and 1999, we are able to estimate household lifetime incomes and then derive a robust estimate of the private saving offset effects of social security retirement benefits. Our estimate is much lower than expected from pure life-cycle considerations (and thus closer to the predictions from Ricardian equivalence theory) and also less than comparable estimates for the US and the UK. This result is thus another proof of a particular "German savings puzzle" [START_REF] Börsch-Supan | The German savings puzzle[END_REF], Börsch-Supan 2001) which might be due to market imperfections and/or bounded rational behavior.

Our study is organized as follows. In Section 2 we review the debate on the real wealth effects of old-age social security, the possible measurements biases and previous empirical findings. In Section 3 we explain our data sample. Section 4 discusses the econometric specification and the results of our empirical test while the last section draws some conclusions.

Wealth effects of old-age security: Theoretical insights, measurement problems and empirical findings

The standard life-cycle model of consumption and wealth accumulation is the most convenient benchmark for the analysis of how an individual reallocates resources in response to the availability of old-age social security or other forms of additional pension wealth. A representative household maximizes lifetime utility subject to a lifetime budget constraint, which depends on exogenous cash F o r P e e r R e v i e w 4 earnings, pension benefits and given interest rates. The resulting optimal consumption and saving path over the whole lifetime implies a complete offset between any kind of pension wealth and non-pension private wealth. As [START_REF] Browning | The life-cycle model of consumption and saving[END_REF] note this is still the baseline result if the model is taken to the data. [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] mentions eight sources of measurement biases that can occur in empirical analyses:

1. Controlling for cash earnings instead of total compensation as the sum of cash wages and pension benefits: Comparing two individuals with equal cash earnings but with different levels of pension wealth, the parameter on pension wealth will pick up not only the substitution effect between pension wealth and non-pension wealth but also the income effect in total compensation. This can lead to an underestimation of the true offset.

2. Ignoring different life expectancy: If one compares two individuals with the same annual pension income and the same retirement age, one can expect that the one with a longer life expectancy will have higher pension wealth and also higher non-pension wealth. To the best of our knowledge, evidence based on survey data for other developed countries is available only in the cases of Israel, Italy, the Netherlands, and the United Kingdom. Building on data from five subsequent Israeli Consumer Expenditure Surveys between 1968[START_REF] King | Asset holdings and the life-cycle[END_REF][START_REF] Lavi | The impact of pension schemes on saving in Israel[END_REF] find offset coefficient in Israel lying between 0 and 0.5. Using the Italian Survey of Household Income and Wealth for the years 1989and 1991[START_REF] Jappelli | Does social security reduce the accumulation of private wealth? Evidence from Italian survey data[END_REF] finds significant displacements effects between social security wealth and private wealth in the range of 10 and 20%. Attanasio and Brugiavini (2003), analysing the effects of the Italian pension reform of 1992, find high offset effects close to the estimates by [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] for individuals in the middle of the life-cycle where [START_REF] Bottazzi | Retirement expectations, pension reforms, and their impact on private wealth accumulation[END_REF] show that the offset effects in Italy are much higher for individuals who are well informed about their future pension benefits than for those who are uninformed. Based on the Dutch Socio-Economic Panel, [START_REF] Alessie | Mandatory pensions and personal savings in the Netherlands[END_REF] find even more than full displacement for social security retirement benefits, but no displacement for occupational pension wealth. Using the CentER Saving Survey, [START_REF] Euwals | Do mandatory pensions decrease household savings? Evidence from the Netherlands[END_REF] is able to show, however, that the impact of the Dutch public pension scheme is not well identified, while for the occupational pensions there is a negative impact only for the highest-income-decile sample. Based on data from the U.K. Family Expenditure Survey, [START_REF] Attanasio | Pension wealth and household saving: evidence from pension reforms in the United Kingdom[END_REF] find a negative impact of the state earnings-related pension scheme (SERPS) on private savings with relatively high substitution elasticities for the older age groups, while for the basic state pension there is no negative impact.

Only [START_REF] Alessie | Mandatory pensions and personal savings in the Netherlands[END_REF], Attanasio and Brugiavini (2003), [START_REF] Attanasio | Pension wealth and household saving: evidence from pension reforms in the United Kingdom[END_REF] as well as Bottazi et al. (2006) make adjustments that correct for the important first measurement problem mentioned by [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF], i. e the bias from controlling for social security wealth and lifetime cash earnings separately. 1 From these studies one gets the impression that the size of the offset effects differs fundamentally between the US and the UK on the one side, and the countries of continental Europe on the other side.

1 The solution proposed by [START_REF] Bernheim | The economic effects of social security: toward a reconciliation of theory and measurement[END_REF], namely controlling for pension wealth and lifetime total compensation instead of lifetime cash earnings, is not a true alternative, since it relies on the implicit assumption of a perfect offset; see Gale (1998, p. 713 f.). Evidence on the size of such offset effects in Germany is still extremely rare. In a time series analysis [START_REF] Kim | Gesetzliche Rentenversicherung und Ersparnisbildung der Privaten Haushalte in der Bundesrepublik Deutschland[END_REF] has shown that the effect of public old-age security on aggregate private capital accumulation in Germany has been relatively low. And we could think of many reasons why market failures and/or bounded rational behavior of households has led to only small offset effects. To give just one example, it has been conjectured by Feldstein (1995, p. 411) that in most European countries the confidence in long-term financial promises of governments is much lower than in the US reflecting the experiences with war, political disorder and inflation over the last century. Germany has been particularly hit by all these developments so that German would consider public pension wealth much less secure than private wealth. Liqudity constraints on underdeveloped financial markets may also have prevented German households from fully substituting private savings by public pension wealth. This is why we would expect that even after controlling for possible measurement biases, the offset effects in Germany are much less pronounced than in the US or in the UK (for the SERPS) or even in other countries of continental Europe.

Data

Sample size

The data for our empirical study come from the German Socio-economic Panel (GSOEP).2 It is the only panel in Germany that provides at the same time information on all the necessary key variables, such as income, non-pension wealth and pension wealth. The successive GSOEP waves from 1984 through 1999 contain data for about 4,500 West German households. GSOEP provides rich socio-economic and biographical information, which are necessary for -The household head is in 1988 at the age between 40 and 59 and works as a full-time employee longer than 1,000 hours each year from 1986 through 1990. 3 If the spouse earns an income, he or she has to work as an employee, too. This excludes households from our sample in which the head or the spouse is self-employed.

-The household head or the spouse was not receiving an old-age pension or a widow's pension in the mandatory German state pension system ("Gesetzliche Rentenversicherung") from 1986 through 1990. We focus on actively working households in order to avoid problems that a different saving behaviour of the retirees might cause.

-Households with missing information relevant for calculating pension wealth, lifetime income or non-pension wealth are excluded.

Our final sample consists of 776 households with 1,304 individuals of which 746 are male and 558 are female.

Household non-pension net wealth

Data on household non-pension net wealth are available in the GSOEP only for 1988. They contain the market value of real estate property (including owneroccupied housing), equity in firms, and financial assets (bank accounts, building savings contracts, and stocks and bonds) less unsecured debt. The market value of real estate property and equity is coded as a categorical variable. The value of financial assets is measured by their exact value if their value is known. Otherwise 3 Excluding the younger employees helps the presence of liquidity constraints to be mitigated. it is estimated by categories. We use all these information for a broad measure of household non-pension net wealth, because -as explained above -narrow measures using just financial assets could cause a significant measurement bias.

So far, a systematic evaluation of the quality of the GSOEP non-pension wealth data does not exist. A comparison by Jürges (2001, p. 396) of the GSOEP wealth data with the 1988 Einkommens-und Verbrauchsstichprobe (EVS), a microcensus by the Federal Statistical Office that provides about 40,000 household data, shows, however, that the GSOEP profile follows the EVS profile rather closely.

For the interest rates until 2005 interest rates for 10 years government bonds are used and a constant interest rate of 3.5% is employed for the years thereafter. In order to check whether or not our results are sensitive to the future interest rate, an interest rate of 5.5% is employed in one of our sensitivity analyses. For the calculation of real values we make use of the German consumer price index until 2005, and a constant value of 2% is assumed for the years after 2005 in accordance with implicit inflation target of the European Central Bank.

Household lifetime income

Estimating lifetime income is essential for testing the offset hypothesis.

According to the life-cycle model lifetime income, and not current income, should be used for testing possible substitution in saving. Other empirical studies estimate lifetime income either based on data from only one year (e.g., [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] or several years (e.g., [START_REF] Jappelli | Does social security reduce the accumulation of private wealth? Evidence from Italian survey data[END_REF][START_REF] Euwals | Do mandatory pensions decrease household savings? Evidence from the Netherlands[END_REF]. [START_REF] Bernheim | The economic effects of social security: toward a reconciliation of theory and measurement[END_REF] uses panel data of a longer time period, but employs a simple extrapolation for estimating yearly earnings in the future. We calculate lifetime income by estimating annual incomes based on the rich information available in the GSOEP. This econometric Because annual income data from 1984 through 1999 were available, income development for the years excluding this period needs to be calculated for each individual. For estimates of annual income before 1984, the activity history by years of age provided by GSOEP is used, while for the calculation of annual income after 1999 it is assumed that the final information on the economic activity and on the kind of occupation also holds true in future years. Following [START_REF] King | Asset holdings and the life-cycle[END_REF], [START_REF] Kazarosian | Precautionary savings: a panel study[END_REF] and [START_REF] Jürges | Do Germans save to leave an estate? An examination of the bequest motive[END_REF]

Public pension wealth and the adjustment factor

The calculation of household public pension wealth is higly complicated by the extreme complexity of the rules (including the many changes of old rules and the introduction of new ones) under which the German social security system operates. We assume for simplicity that all employees start drawing their public retirement benefits at the age of 66, that they expect benefit rules to remain the same in the future, and that public pensions were not taxed in the period under consideration. In the appendix we give a more detailed description of how we calculated social security pension wealth from the GSOEP data.

As [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] has noted, an explicit adjustment factor is necessary to correct the measured values of social security wealth as long as we control for cash earnings and pensions separately. This adjustment factor Q is calculated in the following way:

( 1)/( 1)

xS xT Q e e = - -. (2)
In this formula S measures the years under an old-age pension coverage and T is the sum of S and the expected remaining lifespan.

r x r δ ρ - = -is a discount
factor that is composed of a long-term interest rate r, a rate of time preference δ and a coefficient of risk aversion ρ . In the case of Germany we take r=0. Reflecting the generosity of the German state pension system, household social security wealth is considerable and an important component of lifetime resources.

It is striking that household social security wealth is much bigger than household non-pension net wealth. This reflects the importance of the social security system as a significant source of old-age incomes in Germany. It also implies that a small displacement effect could reduce private household assets by a relatively large amount. It is also interesting that household non-pension net wealth is almost 10 times bigger than financial assets.

< Table 3

Specification

Following [START_REF] Feldstein | Social security and household wealth accumulation: new microeconomic evidence[END_REF], [START_REF] Bernheim | The economic effects of social security: toward a reconciliation of theory and measurement[END_REF] and [START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF], our study employs the following specification to test for the effects of the public pension scheme on household savings in Germany:

,

j j j W Z PQ α β ε = + + ∑ (3)
where the index j = 1, 2 stands for household head and spouse, α and β are parameters to be estimated, and ε is an error term. The dependant variable W is household non-pension net wealth. Z is a vector of variables including household net lifetime income, the age and the squared age of the household head, an interaction term between age and income, years of education (averaged over household head and spouse), a dummy for the marital status, and the number of children. P j is public pension wealth of the household head or the spouse resulting from expected old-age retirement transfers. Q j is the offset factor that should correct for the possible estimation bias due to the use of cash earnings instead of total compensation.

It should be noted that our empirical specification takes into account most of the different sources for potential estimation biases mentioned in section 2. A broad measure of non-pension wealth -household non-pension net wealth rather than financial assets -is used as the dependent variable, and age is explicitly included in the set of explanatory variables. Heterogeneity with regard to choosing jobs

Regression results

Sensitivity Analyses

In order to check whether or not our results are sensitive to the future interest rate of 3.5% p.a., we recalculated the regressions on the basis of a future interest rate of 5.5% p.a. It turned out that for both LAD and robust regressions the main results remain unchanged. The higher interest rate increases the offset effect of social security wealth before adjustment to 23% in the LAD regression and to 14% in the robust regression, while the offset effect after adjustment increases to 30% in the LAD regression and to 19% in the robust regression, respectively.

Concerning life expectancy GSOEP does not provide any direct information.

GSOEP contains just a questionnaire "Have you been suffering for at least a year or chronically from a certain illness or disability?". Using this information we GSOEP provides a questionnaire about expected retirement age, but there are too much missing data. Only 132 household heads answered correctly while 644 did not. Therefore it cannot be tested in this study whether or not retirement age exercises a major influence on our main results. After all, we find it highly plausible -in particular under the German social security regulations -to follow Bernheim (1987, p. 297) who regards retirement age as an endogenous variable that should not be used as an explanatory variable in regressions such as ours.

Conclusions

Our results underline that reactions to social security benefits differ significantly between Germany on the one side and the US, the UK as well as other countries of continental Europe on the other side. Even after making all possible adjustments that could lead to a measurement bias, the offset effect of old-age security on private wealth formation in Germany is not higher than 22% in our base model. It is interesting to note that our panel analysis thus leads to almost the same results as the time-series analysis of wealth effects of the German pension system by [START_REF] Kim | Gesetzliche Rentenversicherung und Ersparnisbildung der Privaten Haushalte in der Bundesrepublik Deutschland[END_REF].

The estimated figures are high enough to make the introduction and enlargement of social security benefits responsible for some part of the reduction in German aggregate capital formation, but they are certainly not an impressive proof of the life-cycle hypothesis. We would rather see our results as supportive to the Feldstein (1995, p. 411) conjectured that given the particular historical and institutional setting of social policy in continental Europe, state provided social security could not be considered a full substitute for private wealth formation.

Explanations of the Geman savings puzzle (Börsch-Supan 1992, Schnabel 1999) point out that the high growth of pension income during the mid 1950s has come as a total surprise to those generations of the war and inter-war times who were not able to change their intertemporal consumption preferences rapidly enough.

Household heads in our sample have been born between 1929 and 1948. Their consumption and saving habits have thus been formed under the experience or in the close memory of extreme political and economic disorder, so that the low confidence in long-term financial promises of the government (or even their overfullfilment) should not be too surprising. However, younger generations that have grown up under the stable economic and political conditions after World

War II behave differently so that the aggregate offset effect can be expected to increase. Future research will have to prove this conjecture.

F

3.

  Omitting retirement age: Generous pension benefits induce workers to retire earlier. At the same time they will accumulate more non-pension wealth for a longer retirement period.4.Omitting age: If one compares two individuals with identical life-cycles, but with different ages, the older one will have less pension wealth and less nonpension wealth than the younger one.5. Ignoring endogeneity of pensions with respect to saving behaviour: One can expect that individuals who tend to save a lot are also more likely to seek jobs pension wealth gross-of-taxes: Measuring pension wealth gross-oftaxes instead of net-of-taxes can generate underestimation of the offset effect. 7. Using narrow measures of non-pension wealth: Smaller offsets are generally found if narrow measures of non-pension wealth are used.8. Measuring pension wealth with error:As pension wealth is difficult to measure, estimates with measurement error will bias the offset effect toward zero.So far most empirical evidence in favour of the offset hypothesis comes from studies based on US data. It is shown by[START_REF] Gale | The effects of pensions on household wealth: a revaluation of theory and evidence[END_REF] that correcting only for the first measurement bias with the help of an adjustment factor increases the measured offset by almost one half (from 0.523 to 0.77). Correcting for the other measurement biases increases the measured offset even further. These results seem to confirm the life-cycle model for the US.

  the least binding.

  and social security wealth. For the selection of our sample the following criteria were employed:

  to reduce the possible measurement error.

  plans is not a serious problem in this study. Since we focus on a social security system which is mandatory for all employees, the households in our sample cannot actively influence their pension rights. Measuring pension wealth gross-or net-of-taxes should not influence the results because social security retirement transfers were tax-exempted in Germany during the relevant period. Measurement error in net social security wealth can be avoided in our estimation because public pension benefits were calculated from the estimates of annual income making use of the rich information in GSOEP and from taking into account the relevant regulations in German social security legislation. The measurement error due to the use of cash earnings is explicitly corrected by the introduction of an offset factor Q. In the following, we present our estimation results with and without an adjustment by the offset factor. There remain two further sources of a potential measurement bias: differences in life expectancy and omission of the effective retirement age. They cannot be taken into account directly in our specification because of a lack of exact information in the available data, but they are dealt with in our sensitivity analyses.

  variable for expected life expectancy in our regressions. It turned out that this dummy is statistically insignificant and that the results concerning offset effect are not modified.

  particular "German savinggs puzzle" as it was characterized byBörsch-Supan et al.(2000, p. 11): "… pensions and health insurance are generous and likely to have large crowding out effects, yet German households accumulate so much real and financial wealth and do not appear to draw it down."

  , our study applies the following estimation equation for the annual income functions:

										11
	< Table 1 >
	F o r
	it x e it E = P ln e χ r + ν	i	+	it e					(1)
	In this equation	R e v
				i e
					w	ν ~	N	(	, 0	δ	2 ν	)	is
	a time-invariant and unobservable individual specific effect resulting from
	education, gender and unobserved skills. it e is an error term. A Hausman test
	strongly indicates that individual effects are not uncorrelated to the regressors.
	Therefore the fixed effects estimates can be employed in our study for calculating

it E ln is the log of net or gross annual income for individual i in year t . it x is a vector of time-varying observable characteristics (including a constant) for individual i in year t , such as a fourth-order polynomial of age, a dummy variable for female household heads, the number and the squared number of children up to age 16 living in the household, and dummies for 10 kinds of occupation. χ benotes the parameter vector to be estimated. i individual annual income. Table 1 shows the estimated determinants of individual gross annual income that can then be used for calculation of public pension wealth.

Table 3

 3 for females according to the German Death Tablein 1986/88provided by the Federal Statistical Office. Table2gives an overview of values of Q that were calculated for German male employees under these assumptions. The

	12
	and 76 years same procedure was also used to calculate adjustment factors for female
	employees.
	< Table 2 >
	F o r
	P
	e
	e r
	R e v
	i e
	w

035, δ=0.02, ρ=3 as baseline values. The total lifespan is 72 years for male employees reports the main sample characteristics concerning lifetime income and various wealth variables for the 776 households. Because only household heads with full-time jobs are considered in our sample, the typical household is relatively affluent. Net social security wealth is calculated by subtracting the present value of future employee contributions from gross social security wealth.

> Page 12 of 28 Editorial

	Submitted Manuscript
	13
	4. Specification and regression results
	F o r
	P
	e
	e r
	R e v
	i e
	w

Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK

Table 4

 4

	provides the econometric results of the least absolute deviation (LAD)
	regressions. Because LAD regressions reduce the effect of outliers, they are useful
	in analysing wealth data, which are typically highly skewed (Engen et al 1994,
	p.105). The estimated social security wealth coefficient without adjustment by an
	offset factor is negative and significantly different from zero at the 1% level. This

implies that public pension wealth reduces non-pension wealth, controlling for other variables, by 16%. After adjustment the offset effect, which is again significant at the 1% level, increases to 22%. The difference between the two

Table 1 :

 1 is expected value of social security pension wealth for individual i in the retirement year t . z is the maximum attainable age. , probability in year t of survival for individual i until the age of k . r is the real interest rate. Finally estimates of social security pension wealth for each employee are measured in DM values of 1988. Regression results for individual gross annual incomes

	o r
	P
	e
	e r
	R e v
	i e
	w

Table 2 : Estimates of the adjustment factor Q for German male employees

 2

	Age when pension	Current age
	coverage began	40	45	50	55	60
	20	0.571	0.668	0.751	0.823 0.885
	25	0.478	0.597	0.698	0.785 0.860
	30	0.362	0.506	0.630	0.737 0.828
	35	0.208	0.387	0.540	0.673 0.787

Table 3 : Household lifetime income and wealth

 3

	Household lifetime income and wealth (in DM values of 1988)	Mean	Standard deviation
	Household net lifetime income	1,290,586 511,287
	net	259,794	133,941
	Household social security wealth
	gross	320,560	134,718
	Household non-pension net wealth	146,755	229,313
	Financial assets	14,988	24,626

Table 4 : Determinants of non-pension net wealth in the LAD regression

 4

				Coefficients
	Independent variables	(t-values in parentheses)
				Unadjusted	Adjusted
	Constant		-13.906 (-2.97)	-14.771 (-3.24)
	Household net lifetime income (in DM values of 1988)	0.049 (1.09)	0.044 (0.98)
	Age			5.331 (2.78)	5.638 (3.02)
	Age2			-0.542 (-2.75)	-0.569 (-2.96)
	Years of education	0.076 (2.24)	0.075 (2.28)
	Age-income interaction	0.013 (3.69)	0.014 (3.92)
	Married			0.443 (2.70)	0.423 (2.63)
	Number of children	-0.080 (-1.43)	-0.076 (-1.38)
	Net social security wealth	-0.162 (-3.47)	-0.218 (-3.48)
	Pseudo	R	2	0.071	0.071
	Number of observations	776	776

Note: Variables are measured in the following units: non-pension wealth, household lifetime income, and social security wealth divided by 100,000, age is divided by 10 and age-income interaction is divided by 10 6 .

Table 5 : Determinants of non-pension net wealth in the robust regression

 5

	Note: Variables are measured in the following units: non-pension wealth, household lifetime
	income, and social security wealth are divided by 100,000, age is divided by 10 and age-income
	interaction is divided by 10 6 .

Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK

Table 6 : Determinants of non-pension net wealth in the LAD regression based on a future interest rate of 5.5% p.a.

 6 : Variables are measured in the following units: non-pension wealth, household lifetime income, and social security wealth are divided by 100,000, age is divided by 10 and age-income interaction is divided by 10 6 .

	Page 27 of 28		Submitted Manuscript
				Coefficients
	Independent variables	(t-values in parentheses)
				Unadjusted	Adjusted
	Constant		-14.483 (-3.39)	-14.867 (-3.06)
	Household net lifetime income (in DM values of 1988)	0.026 (0.58)	0.017 (0.33)
	Age			5.524 (3.16)	5.690 (2.86)
	Age2			-0.558 (-3.10)	-0.577 (-2.81)
	Years of education	0.075 (2.41)	0.075 (2.10)
	Age-income interaction	0.014 (4.22)	0.015 (3.96)
	Married			0.424 (2.82)	0.406 (2.36)
	Number of children	-0.074 (-1.42)	-0.072 (-1.23)
	Net social security wealth	-0.230 (-3.72)	-0.296 (-3.15)
	Pseudo	R	2	0.071	0.071
	Number of observations	776	776

Note

Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK

Table 7 : Determinants of non-pension net wealth in the robust regression based on a future interest rate of 5.5% p.a.

 7 : Variables are measured in the following units: non-pension wealth, household lifetime income, and social security wealth are divided by 100,000, age is divided by 10 and age-income interaction is divided by 10 6 .

		Coefficients
	Independent variables	(t-values in parentheses)
		Unadjusted	Adjusted
	Constant	-10.641 (-2.72)	-10.233 (-2.62)
	Household net lifetime income (in DM values of 1988)	0.024 (0.60)	0.020 (0.49)
	Age	4.101 (2.56)	3.916 (2.44)
	Age2	-0.402 (-2.43)	-0.381 (-2.30)
	Years of education	0.054 (1.91)	0.053 (1.88)
	Age-income interaction	0.007 (2.21)	0.007 (2.26)
	Married	0.520 (3.77)	0.519 (3.77)
	Number of children	-0.086 (-1.80)	-0.086 (-1.82)
	Net social security wealth	-0.141 (-2.48)	-0.188 (-2.50)
	F(8, 767)	10.01	9.92
	Number of observations	776	776

Note

For more information on the GSOEP see www.diw.de/soep. Page 7 of 28 Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK Submitted Manuscript

Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK Submitted Manuscript

Acknowledgements

The authors are grateful to Richard Hauser for very valuable comments and suggestions to earlier versions of this paper. Kim's research was partly sponsored by a grant from German Academic Exchange Service (DAAD) and by the Korea Research Fund.

Appendix

In this study social security wealth is calculated in the same way as in the survey report "Altersvorsorge in Deutschland 1996(AVID 1996)" by the Verband Deutscher Rentenversicherungsträger (VDR) (1999). 4 It is assumed that the insured start drawing their standard old-age pension at the age of 66 and that their further lifetime follows the pattern of the German Death Table ("Allgemeine Sterbetafel") in 1986/88 provided by the Federal Statistical Office. In accordance with AVID (1996), a widow's or a widower's pension is not calculated and a value of zero is put for the pension benefits, if their minimum contribution period of five years is not completed.

First, the monthly amount of a pension at the retirement age is estimated for each individual. The process of calculating the monthly pension in Germany is extremely complex. Thus we briefly explain how we estimated the monthly pension based on the following formula:

where G is personal earnings points, T is pension type factor and C is current monthly pension value.

Income up to the contribution assessment limit for each year is divided by the