You asked
How accurately do the SIC 2007, NACE and ISCI classification applied to companies operating in the UK reflect in distinguishing their actual activities?
As a company develops and evolves, they may drift away from the original classification code. Is it possible that these activities are now so far removed that failing to reclassify will have an adverse effect at the microeconomic level?
If ‘drift’ is prevalent is this data captured within the datasets, if so, is this information available for the years 2009 and 2012/13 for the following SIC groupings:
49.2; 50.2; 50.4; 51.21; 52.2 (less 52.21/2 – 3, 9) and 53.
The main information I require is total GVA, GDP and LFS.
We said
In answer to question 1, company classification on the Business register is initially derived from Companies House. When a company is registered, there is a requirement to specify the SIC code of the business.
The business register uses VAT, PAYE and Company registration, to identify and classify businesses. The industrial classification assigned by HMRC 's VAT system is the primary source of classification. So, the HMRC classification will override the Company House classification.
The administrative data sources (VAT, PAYE, Company Registration) provide classification updates at each delivery. These would mainly be applied to small businesses.
Most larger businesses will also be included in ONS surveys, and the classification will be updated by these. The top priority survey source, is the Business Register and Employment Survey, because this asks businesses to give a business description for each site that they operate. The overall classification given to the company is based on a top down employment rule. So a multiple activity business will be classified to the industry with dominant employment.
These systems ensure that business classification is updated on a regular basis, so we do not monitor drift. Therefore we cannot provide a response for questions 2-4.