In this sense, policies should also be based on statistical evidence, especially when they cover aspects relevant to minority rights and integration, such as ethnicity, language and others, and should also allow for multiple identifications. States enjoy a wide margin of appreciation regarding the instruments and mechanisms for data collection. These might include official censuses. However, censuses should not require compulsory declaration of belonging to specific identities or groups, since nobody should be compelled to declare his or her belonging to a minority.47 Census forms should not limit respondents to closed lists, as self-identification implies also choosing one’s preferred designation.48 Open lists ensure that the results reflect individual choice and also avoid the problem that sometimes groups do not feel represented in official census categories. The questionnaire and census methodologies should be elaborated in consultation with minority representatives and translated into relevant minority languages.49 Censuses are not the only way to collect reliable information about the composition of a population. States should also consider using reliable and objective data collected through other instruments or from other sources, such as independent sociological, ethnographic, linguistic and other scientific research and analysis, as well as household, labour-force, school or other surveys, or data collected by municipalities. Both quantitative and qualitative methods of collection and analysis can provide reliable and thus useful evidence. It is essential that data are collected, processed, stored and used in full compliance with personal-data-protection standards.50 When interpreting data, authorities need to be aware that past experience and fear of discrimination can prompt persons to hide their identity, resulting in underrepresentation of certain groups. In any case, governments should ensure that persons belonging to minorities are aware of the consequences of providing data on their ethnicity and language(s), which can affect language rights, participatory mechanisms and other policies linked to specific demographic thresholds. 47 48 49 50 26 FCNM, article 3(1). UN Principles and Recommendations for Population and Housing Censuses, Rev. 2, 2007 (ST/ESA/STAT/ SER.M/67/Rev.2). Commentary on Language, paragraph 21. These include the Council of Europe’s Convention for the Protection of Individuals with regard to Automatic Processing of Personal Data (ETS no. 108) and the Committee of Ministers’ Recommendation (Recommendation (97)18) concerning the protection of personal data collected and processed for statistical purposes. Useful guidance can also be found in the Conference of European Statisticians’ 2010 Recommendations. Guidelines on Integration of Diverse Societies