Dear Ed, 

 I am writing to inform you of our intention to publish the Trade Union Membership Statistics Bulletin for 2023 as official statistics in development. 

The publication predominantly produces statistics extracted from Labour Force Survey (LFS) microdata from the 4th calendar quarter of each year. The bulletin looks at membership levels and proportions among employees for various categories, such as gender, sector, broad industry, major occupation group, country and region, age group, ethnicity, highest qualification, disability and country of birth. There is a mixture of tables covering time-series and categories in the latest year. 

The LFS suffered a dip in response rates in 2020 when lockdown was introduced due to Covid-19, and response rates have remained lower than prior to Covid. ONS mitigated the impact of lower response rates by increasing the sample to ensure achieved sample levels were met. At the same time ONS has been moving towards the introduction of a Transformed Labour Force Survey (TLFS), which among other aspects would have internet-first collection and a much larger initial sample.  

In July 2023, ONS returned the LFS sample to pre-lockdown levels, primarily to focus more resource on the TLFS due to the potential impending switch to the TLFS. This led to a lower achieved sample which impacted significantly on estimate precision for employment statistics from the LFS. ONS suspended key metrics derived from the LFS microdata in its monthly Labour Market release and commenced an LFS Recovery Plan in October 2023 to increase the achieved response level.  

In its February 2024 Labour Market Statistics release, ONS reintroduced estimates based on the LFS. This was due to some improvements due to the Recovery Plan, and a re-weighting to take account of the latest population estimates. However, the ONS stated that these statistics were accredited as official statistics in development, as measures of statistical precision remained lower than historic measures, and there remained the possibility of short-term volatility in statistics that led to the suspension of LFS estimates in October. Information on the LFS recovery Plan and TLFS progress is reported here. 

As the Trade Union Membership Statistics will use the 4th quarter 2023 LFS dataset for the most up-to-date statistics, and ONS (with OSR agreement) has classified estimates from these data as official statistics in development, our statistics should be similarly classified. We have noted that measures of statistical precision for our key indicators are less precise than for previous years suggesting that our statistics are similarly affected, as expected. We have provided users with background information to the change to official statistics in development. 

 Yours sincerely, 

Jane Naylor 

Chief Statistician, Department for Business and Trade