Several reasons:
- YouGov’s existing data on panellists
- Data from the Electoral Commission
- Linked data sources
The BES includes much of the information that YouGov routinely collects about all members of their panel:
- Age
- Highest qualification
- Home ownership
- Marital status
- Age left education
- Ethnicity
- Local authority and education authority
- Household income
- Personal income
- Household size
- Number of children in household
- Preferred daily newspaper
- Vote choice in 2010
- Religiosity
- Religious denomination
- Type of organisation worked for
- Big 5 personality measures