1. WORKING PARTY ON NATIONAL ACCOUNTS Paris, 3-5 October 2007 Revisions in Quarterly GDP of OECD Countries: An Update Document STD/CSTAT/WPNA(2007)15 Richard McKenzie

2. The OECD Real-Time Data and Revisions Analysis Database Full time series of data published every month starting from the February 1999 edition of the Main Economic Indicators for 21 key economic variables Access OECD revisions analysis studies for GDP, Index of Industrial Production and Retail Trade Volume Automated programs and detailed user guide allowing users to perform their own revisions analysis for any country / variable combination available in the database Enables economists to test the performance of their econometric models in simulated real-time (out-of- sample testing using original first release data)

3. http://stats.oecd.org/mei/default.asp?rev=1

9. Update of Quarterly GDP Revisions Analysis Work done since the presentation at the last meeting: –Added data up to June 2007 edition of the MEI –Revisions analysis extended to reference periods 1994Q4: 2006Q3 (last year: 1995Q1:2004Q4) –Assessment of revisions after 5 months, to capture first revision –Assessment of revision to year-on-year (YoY) growth rates (i.e. 4 quarter rate of change) to complement existing quarter-on-previous quarter (QoQ) growth rates –Results presented in OECD Statistics Working Papers and at various conferences

10. Results Extra one years worth of data doesn’t change things much as the average is over 12 years now –Revisions to first published QoQ growth rates after one year, Finland up a bit ; Norway, Portugal and Korea down Lets focus on the new measures added to the database: size of first revision, revision to YoY growth rates, statistical significance of mean revision at different intervals

11. First revision to quarterly GDP: Relative mean absolute revision to QoQ and YoY growth rates

12. Statistical significance of the mean revision at different intervals

13. Issues for discussion New OECD database interface enabling revisions analysis for components of GDP and other variables Statistical significance of positive mean revision at longer revision intervals for QoQ growth rates –Could this reflect a tendency from the impact of methodological changes? If so, how do we communicate this to users who think there may be a bias? Statistical significance of positive mean revision to YoY growth rates, should we be concerned about these, is more work needed?