London, United Kingdom. British economic growth figures released this week showed the same seasonal pattern for the fourth consecutive year, adding to economists’ concerns about data from the Office for National Statistics.
Repeated quarterly pattern in 2025
Official figures showed that economic growth in 2025 was fastest in the first quarter, second-fastest in the second quarter, and third or fourth-fastest in the third and fourth quarters, as has been the case each year since 2022.
In the October-to-December period of 2025, quarterly growth was 0.1%, compared with 0.7% in the first quarter.
Concerns about seasonal adjustment since the pandemic
Economists said that while such a pattern might be unremarkable as a one-off due to a downturn in a particular year, its repetition has raised concerns that the ONS’ seasonal adjustment has developed a problem since the COVID-19 pandemic.
Statistics agencies in almost all countries adjust data to smooth regular variations such as Christmas shopping, winter heating demand, and summer tourism that can distort underlying trends.
Some economists said the process appears to have been less effective for British data since 2022, making it harder to forecast trends and sometimes making it appear the economy was near recession when it was not.
Impact on policy assessment
Matt Swannell, chief economic adviser at forecasters EY ITEM Club, said it was clear that since the pandemic the first and second quarters have been much stronger than the third and fourth quarters.
He said the pattern distorted perceptions of UK economic performance, making it more difficult for policymakers to assess the growth outlook, and added that it increased uncertainty over when the Bank of England will next cut interest rates.
ONS response
Asked about the pattern, the ONS said it had looked into the issue and that a report published in September found no problem when examining a long historic span of data.
What do you think the ONS should do next to address concerns about seasonal adjustment in UK GDP data?
