Derived variables are variables that are computed from one or more variables.
Some are computed during the interview to control the routing within the questionnaire and can be identified in the questionnaires by searching for “Compute”. Others are computed post-field for the purpose of analysis and are positioned last in the data files with the suffix _dv in the variable name. There are exceptions to this rule. Pointers to significant others in the household (such as the natural parents), based on edited information in the household grid, end on the familiar _pidp and _pno.
Variable search
The derived variables are documented as part of the online variable search and contain notes giving information on how they were derived, for example variable agegr5_dv.
Tips for analysts
Information about how a derived variable is produced is shown in the Derived Variable Note field of the variable. The Variable Search provides descriptive statistics for each variable and, in the Origin field, lists the variables used in the computation of the derived variable. For variables that were computed during the interview, additional information is available in the questionnaires.
Identifiers and other useful variables
Households are identified by “w_hidp”, a wave-specific variable with a different wave-specific prefix for each wave. As shown in the table below, “w_hidp” can be used to link information about a household from different records within a wave. “w_hidp” cannot be used to link information across waves. Since the composition of households changes between waves, the data do not include a longitudinal household identifier.
Individuals are identified by the personal identifier (“pidp”), which is constant in all waves, and can be used to link information about a person from different records belonging to one wave, or to link information from different waves. Individuals are also identified by “w_pno” – the person number within the household. The combination of “w_hidp” and “w_pno” is unique for each individual and can also be used to link information about individuals within a wave.
Useful variables
| Variable | Description | Available in File |
| w_hidp | Household identifier | All files |
| pidp | Cross wave person identifier | All EXCEPT w_hhsamp_ip, w_hhresp_ip |
| w_gor_dv | Government office region (Wave 1) | w_hhsamp_ip, w_hhresp_ip, w_indall_ip, w_indresp_ip |
| w_pno | Person number within the household | All EXCEPT w_hhsamp_ip, w_hhresp_ip |
| w_sex | Sex | w_indall_ip, w_indresp_ip |
| w_dvage | Age | w_indall_ip, w_indresp_ip |
| w_hgpart | PNO of spouse/civil partner | w_indall_ip, w_indresp_ip |
| a_psnenip_xd | cross-sectional person design weight | a_indresp_ip, a_indall_ip, a_youth_ip |
| a_hhdenip_xd | cross-sectional household design weight | a_hhsamp_ip, a_hhresp_ip |
| w_indinip_lw | longitudinal adult main interview weight | w_indresp_ip |
| w_psu | primary sampling unit | w_hhsamp_ip, w_hhresp_ip, w_indall_ip, w_indsamp_ip, w_indresp_ip, w_youth_ip |
| w_strata | sampling strata | w_hhsamp_ip, w_hhresp_ip, w_indall_ip, w_indsamp_ip, w_indresp_ip, w_youth_ip |
Occupation codes
Understanding Society collects free text information on respondents’ job titles and industry. Industry descriptions are coded to ONS Standard Industry Code 2007, or SIC 2007. Job titles are coded to the ONS Standard Occupational Classification 2000, or SOC 2000. Coding is undertaken using the Computer Assisted Structured Coding Tool (CASCOT) system. We use look-up files between SOC 2000 and other classifications provided on the CAMSIS website to derive further occupational classifications.
We provide the following classifications: International Standard Classification of Occupations (ISCO88), Registrar General Social Class (RGSC), National Statistics Socio-economic Classification (NS-SEC), Employment Status (ES), and Socio-economic Group (SEG).
