The Comparative Study of Electoral Systems (CSES) is a collaborative program of research among election study teams from around the world. Participating countries include a common module of survey questions in their post-election studies. The resulting data are deposited along with voting, demographic, district and macro variables. The studies are then merged into a single, free, public dataset for use in comparative study and cross-level analysis. The United Kingdom collaborators are at CREST (Centre for Research into Elections and Social Trends, which is responsible for the British General Election Studies).