The Office for Statistics Regulation has today published a review of the population estimates and projections produced by the Office for National Statistics (ONS). Our review focuses on the population estimates and projections in the context of the principles in the Code of Practice for Statistics.

Population estimates and projections are important data which influence decision making and have implications for many other statistics. The projections feed into local planning decisions which can have a long-term commitment and therefore the impact of issues can have far reaching consequences.

We found good examples of the way ONS produces these statistics including regular engagement with experts, deep dives into individual areas as part of its quality assurance process and through the publication of variant projections to illustrate the uncertainty associated with the statistics.

At the national level, the approach taken by ONS is fit for purpose and is supported by expert advice from demography and academic partners. At the subnational level, the accuracy of estimates is variable due to factors such as the size and mobility of the population in a given area. We found that in some smaller cities that had a large student population, the population estimates did appear to be inconsistent with, and potentially higher than local evidence suggests. More needs to be done to investigate the root and scale of this issue.

We found that there is room for improvement in the way ONS takes on board feedback and handles challenge. ONS should improve its complaints procedure and view challenge as an opportunity to continually develop the statistics and outputs.

We will engage regularly with the team in ONS and continue to monitor the development of these statistics to ensure our recommendations are taken forward. We expect ONS to report back to us with its plans for addressing our findings in July 2021.

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