Survey of Health, Ageing and Retirement in Europe (SHARE)

Overview

The Survey of Health, Ageing and Retirement in Europe (SHARE) is a unique multidisciplinary and cross-national panel database of ex ante harmonized microdata on health, socioeconomic status, and social and family networks covering most of the European Union and Israel. To date, SHARE has collected five waves of data in 2-year intervals since 2004, including current living circumstances and retrospective life histories. A sixth wave is currently (2015) in the field. Four additional waves are planned until 2024.

More than 230,000 interviews conducted so far give a broad picture of life after age 50, measuring physical and mental health, both objectively and subjectively; economic and noneconomic activities, income, and wealth by sources; intergenerational transfers of time and money within and outside of the family; as well as life satisfaction and well-being. The data are available to the scientific community free of charge at www.share-project.org after registration.

SHARE is harmonized with the US Health and Retirement Study (HRS) and the English Longitudinal Study of Ageing (ELSA) and has become a role model for several aging surveys worldwide. SHARE’s scientific power is based on its panel design that grasps the dynamic character of the aging process, its multidisciplinary approach that delivers the full picture of the individual and societal aging, and its cross-nationally ex ante harmonized design that permits international comparisons of health, economic, and social outcomes in Europe and the USA.

Due to their harmonization, the SHARE data and their international sisters encompass a worldwide “historical laboratory” to assess the effects of different policies on health, socioeconomic status, and well-being after age 50. To date (May 2015), more than 1,200 SHARE-based publications assess the chances and challenges of individual and societal aging by exploiting the links between health, economic, and social conditions over the life course observable in SHARE.

Among the key findings is a European North–South gradient in many more dimensions than previously documented. In addition to the well-known income gradient, the health and well-being differences between North and South contradict mortality data and folklore about healthy Mediterranean lifestyle. SHARE has sparked an entire new area of research by revealing a strong correlation between early retirement and the loss of cognitive abilities, social contacts, and well-being. Equally impressive are findings that the large international differences in the uptake of early retirement and disability benefits are more strongly correlated with economic incentives than with health and age.

Background and Development

Population aging is one of the great societal challenges of the twenty-first century. Beginning in the 1990s, this trend mostly affected wealthy countries but is coming up in poorer nations due to their declining fertility rates. According to Eurostat, the rate of older people (65 years and above) in Europe, in relation to persons in their working age, is expected to almost double from 17% in 2010 to 30% in 2060. This is unparalleled in human history and poses big challenges to the welfare state. In 2060, for every one working person, there will be one retired person.

While the demographic trends and its two main causes (low fertility and increasing life expectancy) are clear, not enough is known about consequences and implications of population aging and its manageability through public policy. Understanding how the aging process will affect all of us and disentangling the influences of different cultures, histories, and polices is an important task for researchers in anthropology, demography, economics, epidemiology, gerontology, history, and sociology in order to turn the challenges of population aging into opportunities.

In response to the European Commission’s strong interest in obtaining scientific evidence on population aging in its member states, SHARE was created as a longitudinal survey infrastructure by and for researchers from multiple disciplines (Börsch-Supan et al. 2005). While its development started only in 2002, SHARE has already become one of the crucial pillars of the European Research Area. Since 2012, it is the first ever European Research Infrastructure Consortium (ERIC), with a new legal status and many of the advantages of major international organizations, as well as a long-term perspective up to 2024. The ultimate goal is to provide high-quality microlevel panel data of economic, social, and health factors that accompany and influence aging processes at the individual and societal level. In addition to its multidisciplinary and longitudinal nature, SHARE was set up to be a cross-national enterprise to enable researchers investigating how different European welfare state regimes moderate and mediate consequences and implications of population aging. The data from Europeans aged 50 and over from 18 European countries and Israel are provided free of charge to the scientific community.

Two more features make SHARE a highly valuable source for genuine cross-cultural comparisons. First, SHARE is closely modeled after and constantly harmonized with its sister studies HRS in the USA and ELSA in the UK. This model has sparked and informed exciting new survey research on aging all over the world, e.g., Japan (JSTAR), China (CHARLS), Brazil (ELSI), South Korea (KLOSA), and India (LASI) which puts SHARE into a truly global perspective. Second and as opposed to these global sister surveys, SHARE in itself is a multinational survey. The SHARE interview is ex ante harmonized, and all aspects of the data generation process, from sampling to translation, from fieldwork to data processing, have been conducted according to strict quality standards. Maintaining this ex ante harmonization in spite of national differences and decentralized funding poses great scientific and governance challenges.

Participation and Population Coverage

After five waves of SHARE, more than 230,000 interviews have been conducted with about 86,000 respondents aged 50 and over and their potentially younger partners in 20 countries (Austria, Belgium, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Greece, Hungary, Ireland, Israel, Italy, the Netherlands, Poland, Portugal, Slovenia, Spain, Sweden, and Switzerland). A person is excluded if she or he is incarcerated, hospitalized, or out of the country during the entire survey period, unable to speak the countries’ language(s), or has moved to an unknown address. In addition, current partners living in the household are interviewed regardless of their age. All SHARE respondents that were interviewed in any previous wave are part of the longitudinal sample. They are traced and reinterviewed if they moved within the country (for more information see the SHARE methodology volumes (Börsch-Supan and Jürges 2005; Schröder 2011; Malter and Börsch-Supan 2013)).

SHARE is a multinational survey, which involves differences in sampling resources between countries. Consequently, sample frames are chosen in accordance with the best available frame resources in the country to achieve full probability sampling. Most SHARE countries have access to population registers. SHARE provides sampling design weights to compensate for unequal selection probabilities of the various sample units. Without such weights it is not possible to obtain unbiased estimators of population parameters of interest.

Despite the complexity of the survey instrument and partially decentralized funding, most countries managed to stick to the schedule of having a SHARE data collection every second year. The major exceptions are the later fieldwork periods in Israel in Wave 1 and 2 and, due to funding problems, in Poland in Wave 4. Also, due to lack of sufficient funding following the economic crisis, Greece could not take part in the fourth and fifth waves but is joining again in Wave 6. After merging the Irish SHARE study with TILDA, the Irish Longitudinal Study on Ageing (Kearney et al. 2011), there will be no stand-alone SHARE in Ireland after Wave 3. However, TILDA has taken over substantial parts of the SHARE questionnaire into their study.

The gross samples for the initial wave in 2004 were locally drawn in each of the 12 participating countries. They have been based on sampling frames which acknowledged country-specific circumstances such as the availability of register information, need for screening, expected response rate, etc. This has resulted in more than 50,000 addresses overall. Response rates in the first wave, defined as the proportion of selected households including at least one eligible person from whom an interview was successfully obtained, were about 62% on average. In total, 31,115 interviews were conducted. Existing variation in performance over countries was for the most part consistent with previously known patterns from other international surveys. Cooperation at the individual level was only slightly lower than at the household level. Conditional on household participation an interview could, on average, be obtained from more than 85% of eligible household members.

In the second wave of SHARE, three new countries entered the study. Response rates for the new countries were on average very similar to Wave 1 (about 61%). Additionally, refreshment samples were drawn to increase net sample size and compensate for attrition in the longitudinal sample. Here, response rates were on average a little lower than in the first wave (54%). Individual retention with regard to the longitudinal part of the sample was about 73%. Starting in Wave 2, end-of-life interviews on deceased respondents were administered to relatives or other close persons to the deceased. In total, 34,415 Wave 2 interviews plus 533 end-of-life interviews (EOL) were released, including 18,742 longitudinal interviews. For the third wave, the SHARELIFE study with retrospective life history interviews, no additional households were sampled. 26,836 interviews and 1,139 EOL interviews were conducted in panel households, including 1,158 first interviews with new or previously noncooperating spouses. The resulting individual retention rate was about 77%. In Wave 4, net sample size was substantially increased by including four new countries and drawing refreshment samples in most of the established countries. Altogether, 58,489 interviews, of which 21,566 were longitudinal, and 1,110 EOL interviews were released. Response rates in the baseline (56%) and refresher samples (49%) were on average lower than in previous waves. In this respect SHARE is no exception to the general decline in response rates in face-to-face surveys in Europe and worldwide (Matsuo et al. 2010).

Figure 1 depicts the average retention rate of panel members. It varies a great deal across countries. The average retention rate across all countries and waves is 81%, for the most recently sampled persons 77%. For those interviewed for the first time in Wave 1 (Wave 2, resp.) and reinterviewed in Wave 5, this rate reaches 87% (84%). This reflects the high retention of long-term panel members including the recovery of those respondents who missed a wave. Actually, for every person lost between Wave 4 and Wave 5, almost one person could be recovered from previous waves.

Survey of Health, Ageing and Retirement in Europe (SHARE), Fig. 1

Average 2-year retention rates by sample and country

Since 2005, 11 scientific data releases of the SHARE data were compiled. Figure 2 gives an overview of the released interviews by country, wave, and sample.

Survey of Health, Ageing and Retirement in Europe (SHARE), Fig. 2

Data released in SHARE by country and wave

Variables Collected

SHARE consists of normal panel waves (Waves 1, 2, 4, 5, and 6) and retrospective life histories (Waves 3, repeated for all new respondents in 7).

SHARE panel. Covering the key areas of life, namely, health, socioeconomics, and social networks, SHARE includes a great variety of information: health variables, physical measures and biomarkers, psychological variables, economic variables, and social support variables as well as social network information (see Table 1 for more details):

Survey of Health, Ageing and Retirement in Europe (SHARE), Table 1 Information collected in the SHARE panel Waves 1, 2, 4, 5, and 6

• Health variables include self-reported health, physical functioning, physical measurements such as grip strength, walking speed, peak expiratory flow, chair stand, and body mass index (BMI); health behaviors; and the use of health-care facilities. Wave 6 will add biomarkers extracted from capillary blood such as glycated hemoglobin (HbA1c), a marker of diabetes; C-reactive protein, a marker of cardiovascular disease; cytokines such as TNF-alpha, IL-6, and BDNF, involved in low-grade inflammation, frailty, and cognitive function; and Vitamin D.

• Psychological variables include mental health components such as depression, several tests of cognitive functioning, well-being, life satisfaction, and control beliefs.

• Socioeconomic variables include current work activity, job characteristics, job flexibility, opportunities to work past retirement age, employment history, pension rights, sources and composition of current income, wealth and consumption, housing, and education; in some countries linkage to administrative data on employment, labor income, and pension claims.

• Social support variables include assistance within and beyond families, transfers of income and assets, social networks including ego-centered network size and intensity, and volunteer activities.

The interviewers used computer-assisted personal interviewing (CAPI) to collect most of the data in all waves. In addition self-administered questionnaires (drop-off) were handed out in Waves 1, 2, and 4 after completion of the CAPI. If respondents deceased, EOL interviews were conducted face to face (CAPI) or by telephone (CATI) with a proxy, collecting the information regarding the respondent’s last year of life. Proxy interviews were also used when respondents were not able to do an interview, for example, due to health reasons.

Even though SHARE is a panel survey with a stable core questionnaire over time, innovative research questions, physical measurements, or modules have been incorporated in each wave. For example, in Wave 2, two physical measurements – peak flow and chair stand – were added (see next section for details). In Wave 4 a completely new module – the social networks module based on a name-generator approach – has been implemented to learn more about the social connectedness of respondents. In Wave 6 dried blood spots were taken to measure blood sugar, C-reactive protein, and cholesterol.

To assure an easy and fast entry into cross-national data and high convenience while working with the data, it is necessary that certain variables are readily provided, especially those that allow a valid comparison between countries, such as the International Standard Classification of Education (ISCED). Besides internationally standardized variables, SHARE datasets provide further generated variables that ease or enhance working with SHARE data as well as different kinds of weights and multiple imputations (see the documentation at www.share-project.org/data-access-documentation/).

SHARELIFE retrospective life histories. In SHARELIFE, retrospective data with respect to childhood living circumstances, partners, children, accommodation, employment, and socioeconomic and health conditions were collected with the help of a “Life History Calendar” similar to the one applied in ELSA (Schröder 2011). The combination of the SHARELIFE with SHARE and ELSA data thus gives a detailed picture of the current status of individuals in Europe with a view across their entire life courses (Börsch-Supan et al. 2011). Table 2 provides more details.

Survey of Health, Ageing and Retirement in Europe (SHARE), Table 2 Retrospective information collected in SHARELIFE (Wave 3)

Physical measurements and biomarkers. Until today, physical measurements and biomarkers were mostly taken in smaller, nonrepresentative clinical studies. In the last couple of years, more and more large-scale surveys added physical measurements and biomarkers to their program since standard health questions in surveys are often subject to the respondents’ own interpretation (of the question), own evaluation or perception (of health status), and own knowledge (of health status). The value of subjective health measurements is undeniable, but some research questions require objective measurements. Biomarkers enable researchers to validate respondents’ self-reports and therefore to study the amount and determinants of under-, over-, and misreporting in large-scale population surveys. Biomarkers can help to understand the complex relationships between social status and health and allow identification of predisease pathways, since physiological processes are often below the individual’s threshold of perception. From the first wave on, SHARE combined self-reports on health with physical performance measurements. Dried blood spots have been collected in Germany during Wave 4, and a full-scale collection of dried blood spots in all countries is taking place in Wave 6.

Linking survey and administrative data. Survey data can cover a wide range of topics. However, the information provided by respondents is often incomplete or inaccurate. Administrative data on the other hand are much more complete and accurate since they are process generated. The disadvantage of administrative data is that the information is limited to certain topics only. Linking survey data with administrative data is a way to combine the best of both worlds. SHARE thus cooperates with the German Pension Fund (DRV) and has linked the German survey data with administrative data held by the DRV in a pilot study in the third wave of SHARE. The administrative data consists of two parts: The first part is longitudinal and includes sociodemographic characteristics (such as age, sex, number and age of children, and education) and detailed information about the working history as well as all activities which generate public pension entitlements. That data is implemented as a panel database beginning at age 14 which provides that information on a monthly base. The second part is cross sectional and only available for retirees. Included is information on the calculation of the pension benefits. The two datasets are updated every year (Korbmacher and Czaplicki 2013).

Data Usage

Access to the infrastructure via two data archives is free for all scientists globally, subject to European Union data protection regulations: http://www.share-eric.eu.

The scientific power of SHARE is based on three elements: its panel design which grasps the dynamic character of the aging process, its multidisciplinary approach which delivers the full picture of the aging process, and its ex ante cross-national harmonization which permits rigorous benchmarking and policy evaluation across countries. Such a data set takes time to build up. Since 2004, when SHARE was started, the number of countries almost doubled from 11 to 20.

SHARE has succeeded surprisingly fast to create a large user community. Since the first public release of SHARE data in April 2005, SHARE has attracted more than 4,300 registered users with an unbroken, more than linearly increasing trend. Since we count registrations not including work students and students in class, we estimate an approximate number of 10,750 actual users. While users include mainly scientists from Europe, researchers from the USA are now the second largest user group after Germany, before Italy and the Netherlands. We interpret the acceptance of SHARE by so many researchers, and particularly in the USA, as an indicator of SHARE’s high scientific value.

Arguably the best indicator for the success of a research infrastructure is the number of published findings emanating from it. In addition to four comprehensive volumes of first results from the SHARE baseline, longitudinal, and retrospective waves (2004–2012) which have been complemented by several national collections of findings, more than 50 books and 1,000 articles in peer-reviewed journals and volumes have been published based on SHARE data. This is the current state. Based on the experience of other panel data, their usefulness and thus user and publication numbers will increase steeply with the number of future waves.

SHARE has generated some surprising findings which have received wide-spread attention. Three examples may show the breadth and quality of successful SHARE-based research:

• Already the first wave of data revealed a European North–South gradient in many more dimensions than previously documented. While the income gradient was known, thanks to earlier Eurostat data, the health and subjective well-being differences between the North and the South of Europe were a surprise because they contradict mortality data and folklore about healthy Mediterranean lifestyle. These findings pose new fundamental questions, e.g., about the economic, social, and medical causes for a divergence between mortality and morbidity.

• Another surprising finding from SHARE has sparked an entire new area of research and a lot of controversy: SHARE data revealed a strong correlation between early retirement and the loss of cognitive abilities both within and between European countries. A fruitful cooperation between cognitive psychologists, gerontologists, economists, and sociologists has begun to identify the causes for this finding which range from the cognition-stimulating effect of work even if it is unpleasant to the social isolation experienced by many retirees. It sheds new light on the EU’s strive for active aging.

• Equally surprising is the finding that the large international differences in the uptake of disability benefits are not at all correlated with health or demographic differences in Europe, such as those mentioned above between the North and the South. Rather, they are almost completely explained by the different rules and regulations of the various disability insurance schemes in the member states and document how powerful economic incentives are for retirement behavior.

Many of the SHARE findings have strong policy implications for aging societies, such as tighter targeting rules for disability insurance or a stricter handling of early retirement pathways. SHARE has been successful in providing help for evidence-based policy making, both at the European Union and the member state level. SHARE is also intensely used by the Organisation for Economic Co-operation and Development (OECD) and the World Health Organization (WHO).

Acknowledgments

During the first three waves, the SHARE data collection has been primarily funded by the European Commission through the 5th framework programme (QLK6-CT-2001- 00360 in the thematic programme Quality of Life), through the 6th framework programme (SHARE-I3, RII-CT- 2006-062193, COMPARE, CIT5-CT-2005-028857, SHARELIFE, CIT4-CT-2006-028812) and through the 7th framework programme (SHARE-PREP, 211909, SHARE-LEAP, 227822). Starting with Wave 4, SHARE has changed to a decentralized funding model and became an international organization („SHARE-ERIC”) funded by its member countries. Substantial additional funding comes from the US National Institute on Aging (U01 AG09740-13S2, P01 AG005842, P01 AG08291, P30 AG12815, Y1-AG-4553-01, OGHA 04-064, IAG BSR06-11, R21 AG025169). The German Federal Ministry of Education and Research is funding the Munich-based international coordination of SHARE (AZA 01UW0908) while the EU Commission finances all coordination elsewhere (SHARE-M4, 261982). We gratefully acknowledge these as well as all national funding sources (see www.share-eric.eu for a full list of funding institutions). This article is based in parts on an updated version of Börsch-Supan et al. (2013).