The data collected in each wave is provided in a set of datafiles where roughly each file includes information collected from one source. To make it easy for data users, files have the same root name but a letter prefix signifies the wave that this file pertains to. So, information collected from youth respondents using the youth questionnaire is stored in the data file with the root name youth. The name of the data file for this information collected in Wave 1 is a_youth, in Wave 2 b_youth and so on. Since November 2018, 18 waves of BHPS datafiles which have been harmonised (with a few exceptions) have also been released along with Understanding Society data. These data files have similar structure, but their names start with prefixes ba_ bb_ bc_…. until br_. See the BHPS – Harmonised User Guide for further details.
Some datafiles include information that was collected across multiple waves and are not specific to any particular wave. These files have names starting with the letter “x” to indicate these are the cross-wave files, that is, they include data collected from different waves. For example, the datafile xwavedat time fixed information such as date or birth, country of birth, parents’ occupation when the person was 14 years old. These types of information are only collected once, generally the first time a person is interviewed. Although most people were interviewed for the first time in Wave 1, others who join the households of the core sample members after Wave 1, were asked in the wave they joined. So, this file puts this data collected in different waves together in one file.
