Export Statistics Scotland: methodology

ESS processing: grossing and imputation

At this stage in the data processing there are still many businesses without export proportions, so we obtain these proportions in one of two ways. Firstly, if a business has responded to a GCS in previous years, we can use their response from the nearest year. For example, if a business had responded to the GCS in 2020 but not 2021, the export proportions from 2020 could be used for 2021. That export proportion would then be used with their 2021 turnover value to produce an estimated value for exports in 2021. Preference is given to the most recent year when imputing values from previous years.  

Secondly, for businesses that have never responded to GCS, we can use information we have already collected for businesses with similar characteristics, to estimate export proportions via grossing. 

To estimate the proportion of a business’ turnover accounted for by exports, we first group all businesses in the ESS population by their characteristics, including if they export, the year they are operating in, Standard Industrial Classification (SIC), geographic information and number of employees. 

If a group includes at least 10 businesses for which we have export information, we calculate the average (mean) export proportion of these businesses within each group. This export proportion is then imputed for all the other businesses in the same group for which we do not have an export proportion.  

This process is then repeated multiple times, each time using less stringent criteria for matching businesses into groups. For example, in earlier stages the process starts by matching on 5 digit SIC code (which is more specific) and with narrow bands for number of employees (for example 50 employees per band) and then in later stages matching occurs on 3 digit SIC code (which is less specific) and with wider bands for number of employees (for example 100 employees per band). These wider bands increase the likelihood of a business being captured in a group.  

If after this process a business has still not received an export proportion from a matching group, they are then matched on 3 digit SIC and year only, and the requirement for 10 businesses per group is dropped. Ultimately, all businesses in the ESS population have an export proportion assigned. This process is carried out separately for the different export destinations: international, rest of UK, EU and non-EU, as well as world regions and individual countries. 

This export proportion is then used to calculate an export value from the turnover for each business in the population. These are summed to produce the estimated export values for Scotland presented in the published Excel tables and the ESS publication.