Changing Industrial Classification to SIC (2007) at the UK Office for National Statistics

As part of the changes to industrial classifications following the United Nations’ revision to the International Standard Industrial Classification, ISIC Rev. 4, the UK moved to its version of a new classification between 2007 and 2011. We describe the processes involved in changing an industrial classification, including model-based adjustment methods and changes to survey designs and operations. We discuss the quality of the approaches used for different time periods in the same series, and the ways in which consistent time series are produced for users of economic statistics. We provide some general evaluation of the changeover, and guidance on the best approaches to follow when updating classifications.