The Census of Population and Housing is one of the most important surveys carried out by ISTAT. It is conducted every ten years from 1861, and the main objectives are: - the count of the whole population and the recognition of its structural characteristics; - updating and revision of civil registers; - the definition of the legal population for juridical and electoral purposes; - the collection of information about the number and structural characteristics of houses and buildings; The Census collects information about demographic and family structure of the population, the types of their households, their level of education, their employment status, and other informations on residents population. Through the 15th census, Istat were introduced some methodological and technical innovations, designed to simplify the organizational impact on municipalities, enhancing administrative data, retrieve timeliness in the dissemination of the final data, reduce the statistical burden on families. In 2011, for the first time, some information of socio-economic character were measured on a sample basis through the use of two types of questionnaire: one in a reduced form, with a few questions, including indispensable information for the production of the data required by the European Union with an high spatial detail, and one in complete form. The questionnaires have been prepared taking into account national and European legislation, the new detection strategy, the need to ensure international comparability, the demands of the users of census data and to ensure the continuity of some time series.

In urban areas with at least 20,000 inhabitants a sample was selected by a simple random sampling without replacement procedure of one third of the families. A complete version (long form) of the questionnaire has been sent to the sample, while a short version the questionnaire has been sent to all other inhabitants.

self-administered questionnaire