2011 Census data on language : Different questionnaires, different results

The historical comparability of data from different censuses requires that we take into account all changes that may have arisen during the period under study. The way in which we answer the census of population questionnaire or to any other surveys may in fact be influenced by various factors, including those related to the methodology. The examination of the responses to the language questions of the 2001, 2006 and 2011 censuses allows us to note that observed changes in the patterns of response to the questions on mother tongue and language spoken at home in 2011 arise in large part from the changes made to the position and context of the language questions in this census questionnaire relative to previous censuses.