The TwinLife data is available free of charge and can be accessed via GESIS after filling in the ➔ Data Use Agreement. The data delivery consists of a certain number of data files in SPSS and Stata format:

• Master data (ZA6701_master_v$): Includes information on the gross sample, such as consistency checked variables that are stable over time (sex, year of birth, relation to the twins, zygosity, migration background) and wave-specific variables (person type, response status, family composition) about all individuals included in TwinLife in each wave.

• Survey data in person format (ZA6701_person_wid$_v$): There is one data set for each data collection (F2F 1, CATI 1, F2F 2). Each surveyed person has one data row. The data collection identifier is the variable wid.

• Survey data in family format (ZA6701_family_wide_wid$_v$.dta): There is one data set for each data collection (F2F 1, CATI 1, F2F 2). Each family has one data row with information of each participating person in the family being stored in separate variables/columns). See chapter 3.3 for more detailed information. Person format and family format data sets contain the same data using different structures.

• Twin zygosity assessment (ZA6701_zygosity_v$): A data file with the information of the twin zygosity assessment in F2F 1.

• Unadjusted data of all variables collected in the PAPI survey mode (ZA6701_person_unadj_wid1_v4-0-0.dta): One data file for each data collection with data unadjusted for filter errors for all constructs/variables that were at least partly surveyed in the PAPI mode (as of data release v4-1-0 in autumn 2020). See chapter 4.2 for further details.

All data is provided with English and German variable descriptions. In Stata, these languages are included in one data set while in SPSS, these are separate data files. The data are checked for inconsistencies and adjusted for filter errors (for details see chapter 4).