The Office for National Statistics (ONS) conducted several tests to inform the design for the 2011 Census. These tests allowed ONS to assess plans, questions, quality of responses, performance of suppliers, and the viability of the innovative elements of the design.
The lessons learned are included in the evaluation reports, available to download.
2007 Census Test
The first major field test involved 100,000 households in Bath and North East Somerset, Camden, Carmarthenshire, Liverpool and Stoke-on-Trent. ONS tested three things: whether questionnaires could be posted to households and the resulting impact on return rates (in previous censuses, questionnaires have been hand delivered), the effect on return rates of asking an income question, and the viability of outsourcing recruitment, pay and training. The conclusion was that both post out and the outsourcing of recruitment, pay and training worked but that including an income question reduced return rates - hence the 2011 Census questionnaire did not include an income question.
The 2009 Census Rehearsal was carried out on Sunday 11 October in Ynys Mon/ Isle of Anglesey, Newham and Lancaster. Around 135,000 households and hundreds of communal establishments of all types were included in the rehearsal. The purpose of the 2009 Rehearsal was to replicate the systems and processes that would be used for the 2011 Census. The findings from this helped finalise and improve the 2011 design. Internet completion and online help were used for the first time. Census HQ worked closely with each of the local authorities and community groups and this helped to inform and fine tune engagement plans for the 2011 Census.
Small scale tests (SSTs)
In addition to these large exercises, a series of smaller tests were conducted to try different procedures and questions. These tests were held in various parts of the country and covered accommodation types and population groups.