The Census collected information on the resident population of Northern Ireland on Census Day (27 March 2011). Questionnaires were delivered to every household and communal establishment and residents asked to complete and return with information as correct on Census Day. Special arrangements were made to enumerate special groups such as the Armed Forces. The Census Coverage Survey (an independent doorstep survey) followed between 9 May and 3 June 2011 and was used to adjust the Census counts for under-enumeration.
