FOI reference: FOI-2025-3332
You asked
Under the Freedom of Information Act, please provide me with the criteria used in your selection process and the percentage of Small and Medium Enterprises (SMEs) required to complete the surveys.
We said
Thank you for your request.
Businesses are selected for ONS economic surveys either: with certainty, generally if they are large and/or unique; or randomly, generally if they are smaller and/or similar to other businesses. If selected with certainty, a business will always be selected for the survey (or surveys). If selected randomly, after a pre-defined number of questionnaires have been sent, the business will cease to be sampled and will be replaced by a similar business – also randomly selected. ONS conducts over 70 economic surveys, and the same business can be selected randomly in multiple surveys over multiple periods. We do manage burden, and this means that after a time businesses will be rotated out of the sample and won't be reselected for a number of years afterwards. Only a small proportion of similar businesses are expected to be in a survey at any one time, and this proportion varies between surveys due to differing quality requirements.
ONS classify businesses by employment size band – usually 0-9, 10-19, 20-99 and 100+, and sample at different rates in each of these. For a business with between 20 and 99 employment (what we would view as a 'medium' sized business), the general rule is that it should reside in our samples for monthly or quarterly surveys for up to 27 months, or 9 quarters, before being rotated out and replaced by a similar sized business from that same industry. Over time, this ensures fairness of selection – but in the short term a business might find itself selected for more ONS surveys than a similar sized business operating in that same industry. On rare occasions, it is possible for a smaller business to stay in our samples for a longer period – but this usually occurs when they operate in a niche industry.
You can find more information about the selection process on our website.
The likelihood of selection per employment band
We do not hold analysis to definitively show the percentage of SMEs required to complete our statistical surveys within the designated timeframe. We can say, however, that the probability of selection increases the larger a business is in terms of people employed. If you are a business that employs over 99 people, you are guaranteed to be selected for a range of business surveys and will not be rotated out of our samples while your employment stays at that level or above.