The calculated calendar year growth rates for 2009 published in the OECD’s latest interim economic assessment are computed by mechanically extending the GDP outturn data up to the second quarter of 2009 with the model projections for the third and fourth quarters. This means that differences between the 2009 forecast for GDP published in the OECD June Economic Outlook and the latest interim economic assessment reflect both revisions in historical data and the Q3 and Q4 GDP projections. For some countries, historical data revisions account for a large part of the change in the 2009 projection. In the United Kingdom, for example, the calculated calendar year growth rate is weaker than the one in the June Economic Outlook, despite the estimates for the 3rd and 4th quarter being higher than the corresponding projections in the June Economic Outlook. This reflects downward revisions for historical growth rates for, in particular, the fourth quarter of 2008 and the first quarter of 2009. It should also be noted that the calculated calendar year growth rate for 2009 for Canada should read -3.0.