REWRITING HISTORY: Sixty-plus years of major revisions to official UK GDP numbers
- 25 Mar 2015
Many times since annual publication of official GDP numbers began in 1948, there have been major subsequent revisions, which in a sense are rewriting history. That is the finding of new research by Enrico Berkes and Samuel Williamson to be presented at the Economic History Society’s 2015 annual conference. Their study does three things:
- First, it reports on the authors’ compilations of all the official versions of GDP that have been published since 1959 that they are now making available online.
- Second, it discusses the impact that these numbers had when they were published and if subsequent revisions would have changed the conclusions made at the time.
- Finally, it discusses the large revisions of the last three years and the implication for the current interpretation of post-war growth.
The research on these data sets shows that some events that might seem uncorrelated with GDP measurement have an impact on revisions of GDP data. In particular, the researchers show that in periods of recessions and periods around the elections before 1997, the revisions have been higher and sometimes followed a precise pattern.
The authors’ particular concern for the numbers published in the last three years is that, even after correcting for an production error (announced last fall), the new series increases the annualised growth rate of per capita real GDP from 2.06% to 2.25%, thus projecting backwards that the 1948 per capita GDP was 14% lower than it had been predicted the year before.
For over 60 years, the official GDP numbers for the UK have been published annually by a government office – since 1997, the Office for National Statistics (ONS). For the most part these series start in 1948 and end in the previous year. As with most official numbers, one can expect there to be minor revisions of the series from year to year. This study shows that many times these revisions are far from minor.
'Years of Revisions in the Official Estimates of GDP for the United Kingdom: Their Impact on the Interpretation of Post War Economic Performance'
Enrico Berkes and Samuel H. Williamson