FOI REF: FOI/2022/4658
You asked
I wish to understand the adjustments applied to the raw 2021 census figures for Coventry, Warwick DC, Nuneaton and Bedworth, Rugby, and Stratford upon Avon. Would you please send any evidence (from surveys or other information) and any commentary, (emails, reports, notes) which specifically explains and justifies the adjustments made for these local authorities.
We said
Thank you for your query regarding adjustments applied to the raw 2021 census figures for Coventry, Warwick, Nuneaton and Bedworth, Rugby, and Stratford-upon-Avon.
The collected census data undergoes substantial processes before the final estimates are published as described in Maximising the quality of the Census 2021 population estimates. These processes are generally standard across all local authorities and documents relating to those methods and their application would not be specific to individual local authorities with the exceptions noted under additional methods below.
Most notably, these processes include estimation of, and adjustment for, undercoverage and overcoverage in the collected data. Detailed descriptions of the methods used for this are described in Coverage estimation for Census 2021 in England and Wales.
As described in that document, the standard coverage adjustment methods were complemented by additional methods where necessary. These additional methods were implemented for the Local Authorities (LA) you mention only for the adjustment for 0 to 2 year olds which was applied to every LA.
We have published the size of the different types of adjustment for each of the LAs you mention in our LA comparison tool. The adjustment for 0 to 2 year olds described above is equivalent to the 'Other local adjustments' figure in Table W01 for the LAs you mention. This adjustment increased the population of each LA you mention by less than 0.2% of the initial estimate.
Adjusting the raw census data so that the final census results reflect the entire population is a very complex procedure with many different aspects within the overall census process. We understand that in order to fulfil our underlying commitment to transparency, we must allow for a certain level of disruption, particularly where a request has a serious purpose and value to the public. We appreciate that the topic of your request does have a serious purpose and value, as the census is essential to help the government and local authorities to plan and fund local services.
However, this purpose has been fulfilled by the information provided in the reports linked above which explain in detail our processes for making adjustments to our census figures. Furthermore, the task of searching for, extracting, and collating this information would be burdensome and disrupt our functions. The scope of this request would cover at least 6 years' worth of information and would require the search of the personal workspaces, email accounts, desktops, SharePoint files, shared drives, and physical notebooks of individuals spanning across many teams. Many team members will have moved on to other business areas, or left the organisation, making this task even more logistically difficult. We estimate that this search would cover thousands of documents, so even once the search for the information is complete, the exercise of collating the information would be equally burdensome.
We believe this burden would be disproportionate when weighed against the value of this information. Therefore, this information is exempt from disclosure under Section 14 (1) of the Freedom of Information Act 2000 (FOIA).
However, we hope that the documents provided in this response will help with understanding the adjustments made.