in Northern Ireland in 1931, but one took place there in 1937. Coverage In 2001, the census form was completed by 94 per cent of the population in England and Wales, with a further 4 per cent identified by the census enumerators, though the results still represented 100 per cent of the population through the use of cross-matching with a follow-up survey. The Census Act 1920 (as amended) legislates a fine of up to £1,000 for those who refuse to complete their census forms. In some censuses, significant numbers of people intentionally did not participate for political reasons. In 1911, the Women's Freedom League, a suffragette organisation campaigning for female suffrage in the United Kingdom, organised a boycott of the census. They encouraged women to go to all-night parties or to stay at friends' houses to avoid the census and some heads of households refused to report the women at the address. In 1991, many people again avoided the census, which was conducted during the time of the poll tax debate, in case the government used it to enforce the tax. It was estimated that up to one million people were not counted by the 1991 census due to such evasion. Criminal law Under section 8 of the Census Act 1920, whoever refuses or neglects to comply with the census, makes a false declaration, makes, signs, or delivers a false document, or causes the same, or refuses to answer, or gives false answers, shall be liable on summary conviction and face a maximum fine of £1,000. Exceptions exist for refusing or neglecting to respond to questions about religion, as stipulated by the Census (Amendment) Act 2000. Data sets Traditionally, outputs are released in the form of tables of counts at various levels of geography. However, microdata, known Samples of Anonymised Records (SARs) are UK data-sets consisting of samples of individual records from national censuses. These very large datasets resemble survey data and are used for a range of applications by social scientists and policymakers. The first SAR was released in 1991. In 2001, the SAR system was extended, and it is anticipated that there will be SAR files from the 2011 census. 2001 The 1851 census included a question about religion on a separate response sheet, whose completion was not compulsory. However, the 2001 census was the first in which the government asked about religion on the main census form.