The SOEP started in 1984 as a longitudinal survey of private households in the Federal Republic of Germany. The central aim then and now is to collect representative micro-data to measure stability and change in living conditions by following a micro-economic approach enriched with variables from sociology and political science (influenced by the “Social Indicator” movement). Therefore the central survey instruments are a houeshold questionnaire, which is responded by the head of a household and an individual questionnaire, which each household member is intended to answer. Furthermore beginning with 1997, there are wave-specific $LELA files (Lebenslauf - engl. life course) containing the biography information as collected in the respective year.
A rather stable set of core questions is asked every year covering the most essential areas of interest of the SOEP:
Additionally, yearly topical modules enhance the basic information in (at least) one of these areas by asking detailed questions as documented in Table 1 and Figure 1. These modules for the main part appear in the personal questionnaires; only some of them are additions to the household questionnaire. Starting in the year 2001, the data have become even richer by including several different health measures and well-known psychological concepts as well as age specific questionnaires.
Table 1: Overview of Supplementary Questionnaires 1986-2012
| Year | Wave number | Wave letter | Topic | |
|---|---|---|---|---|
| 1986 | 3 | C | Residential environment and neighborhood | |
| 1987 | 4 | D | Social security, transition to retirement | |
| 1988 | 5 | E | Household finances and wealth | |
| 1989 | 6 | F | Further occupational training and professional qualifications | |
| 1990 | 7 | G | Time use and time preferences; Labor market and subjective indicators | |
| 1991 | 8 | H | Family and social networks | |
| 1992 | 9 | I | Social security (2nd measurement) | |
| 1993 | 10 | J | Further occupational training (2nd) | |
| 1994 | 11 | K | Residential environment and neighborhood (2nd); Working conditions; Expectations for the future | |
| 1995 | 12 | L | Time use (2nd) | |
| 1996 | 13 | M | Family and social networks (2nd) | |
| 1997 | 14 | N | Social security (3rd) | |
| 1998 | 15 | O | Transportation and energy use; Time use (3rd) | |
| 1999 | 16 | P | Residential environment and neighborhood (3rd); Expectations for the future (2nd) | |
| 2000 | 17 | Q | Further occupational training (3rd) | |
| 2001 | 18 | R | Family and social networks (3rd) | Working conditions (ERI) |
| 2002 | 19 | S | Wealth and assets (2nd); Social security (4th); Health (SF12, BMI) | |
| 2003 | 20 | T | Transportation and energy use (2nd); Trust; Time use (4th) | |
| 2004 | 21 | U | Residential environment and neighborhood (4th); Further occupational training (4th); Risk aversion; Health (2nd) | |
| 2005 | 22 | V | Expectations for the future (3rd); Big Five; Reciprocity | |
| 2006 | 23 | W | Family and social networks (4th); Working conditions (ERI) (2nd); Health (3rd); Grip strength | |
| 2007 | 24 | X | Wealth and assets (3rd); Social security (5th) | |
| 2008 | 25 | Y | Further occupational training (5th); Health (4th); Grip strength (2nd); Trust (2nd); Time use (5th) | |
| 2009 | 26 | Z | Residential environment and neighborhood (5th); Risk aversion (2nd); Big Five (2nd); Globalization and transnationalization; Diseases | |
| 2010 | 27 | BA | Consumption and saving; Reciprocity (2nd); Health (5th); Grip strength (3rd) | |
| 2011 | 28 | BB | Family and social networks (5th); Working conditions (ERI) (3rd); Diseases (2nd) | |
| 2012 | 29 | BC | Wealth and assets (4th); Social security (6th); Health (6th); Grip strength (4th) | |
| 2013 | 30 | BD | Big Five (3rd); Trust (3rd); Loneliness; Diseases (3rd) | |
| 2014 | 31 | BE | Health (7th); Risk aversion (3rd); Globalization and transnationalization (2nd); Residential environment and neighborhood (6th); Grip strength (5th) | |
| 2015 | 32 | BF | Minimum wages; Reciprocity (3rd); Diseases (4th); Transportation and energy use (3rd) | |
| 2016 | 33 | BG | Minimum wages (2nd); Health (8th); Family and social networks (6th); Working conditions (ERI) (4th); LGBT; Grip strength (6th) |
Since the year 2000, youths (turning 17 during the survey year) form a new group of respondents with a specific questionnaire suited to their situation. The questions cover their situation at home, including the relationship to their parents and friends. School and job aspirations are a major part, while some of the psychological measures available for the adults (e.g. Big Five, risk aversion) are also taken. Overall, the youth questionnaire provides a broad overview of the individual’s situation at a very interesting and potentially influencial point in their life.
Since 2003 SOEP also asks parents about their young children, by implementing age specific questionnaires. In 2003, a first questionnaire was added for infants and very young children born during the current or previous survey year. Since then, four additional questionnaires have been added for children in different age groups. In 2012, parents were asked about their children turning 10 during the current survey year for the first time. The topics in these questionnaires vary with the age of the child - for an overview, see Table 2.
Table 2: Overview of Proxy Questionnaires for Young Children
| Questionnaire | Age Group (years) | First used in | Respondent | Topics |
|---|---|---|---|---|
| Mother-Child A | 0-1 | 2003 | Mother | Child Health; Circumstances of Pregnancy; Child Care |
| Mother-Child B | 2-3 | 2005 | Mother (Father) | Child Health; Child Care; Compentecies |
| Mother-Child C | 5-6 | 2008 | Mother (Father) | Strengths and Difficulties (SDQ); Child Health; Child Care; Activities |
| Parent-Child D | 7-8 | 2010 | Mother and Father | Educational Goals; Upbringing Styles and Goals; Child Care |
| Mother-Child E | 9-10 | 2012 | Mother (Father) | Educational Goals and School Performance; Activities; Child Health; Strengths and Difficulties (SDQ); Child Care |
(Note that for all questionnaires except the Parent-Child D the mother is the first choice to fill out the questionnaire, whereas the father is meant to answer only if the mother is not available.)
Especially Table 1 shows that the SOEP evolved in various directions over the course of its existence. New topics will continue to be introduced in future waves of data collection, depending on what is important for the scientific community.