Annual Population Survey (APS)
On Wed 18 March 2015 ONS revised estimates derived from the Annual Population Survey (including estimates of employment, unemployment and economic inactivity) as a result of taking on board population estimates based on the 2011 Census. Estimates are revised back to January to December 2004. These revisions are in line with similar revisions to Labour Force Survey estimates published in the October 2014 UK Labour Market and Regional Labour Market Statistical Bulletins.
This revision affects the main Annual Population Survey dataset, the APS workplace analysis and the Model-based Estimates of Employment.
An article, further explaining this re-weighting exercise is also available. (http://www.ons.gov.uk/ons/guide-method/method-quality/specific/labour-market/subnational-labour/reweighting-article.pdf)