4. The electoral roll is a survey that a local government do to measure how many voting people there are in a city.
5. The census is a survey that the national government do to measure how many people live in a city and other characteristics.
7. The
civil registry is an agency, which write down the important events in the
lives of its population, for example births, deaths and marriages.
Para entender los porcentajes de las encuestas en España, hemos visualizado un vídeo que simplifica las estadísticas españolas como si esta fuera un país de 100 habitantes.
https://www.youtube.com/watch?v=LJpFD1pLmFA