The ➔ Codebooks give an overview of the variables included in the current data release of the person files of the data collection (for the structure of the delivered data, see chapter 3.1) and their frequencies. The variables are sorted alphabetically within content-related chapters. The codebooks document the following information for these variables:

• variable name
• variable label (also includes information on age groups and person types surveyed)
• question text
• categories (including the value labels) and frequencies
• waves the variable was surveyed in
• filter conditions based on the instruments used for the variable
• sources for additional information

The codebooks for all data collections can be found in the ➔ Downloads section of the TwinLife Data Documentation website.