Once the sample of registered electors has been selected, whether they have participated in the elections or not is recorded by the officials of the INSEE regional directorates, by consulting the lists of actual voters within ten days of the vote, as any elector is entitled to do.

These lists are consulted at the prefecture for national votes. The same sample of electors can be monitored over several annual votes.

The general list of electors features little socio-demographic information (age and gender, municipality of registration, municipality of birth). In order to have further information, such as socio-professional category, qualifications or family situation, it is matched with selected information from the permanent demographic sample (EDP).

The EDP combines, for a sample of the population, information from vital event registers, census data and the elector register, a panel on wage earners and some fiscal data and the standard of living. As the sample is based on the date of birth of the people, it is easy to restrict the sampling frame of the electoral survey to electors liable to be included in the EDP sample.