Statistics New Zealand has made some big revisions to the history of the country's gross domestic product (GDP) growth figures.
After the revisions, SNZ said GDP growth over calendar 2011 came to 1.1 per cent, down from a previously published figure of 1.4 per cent.
Economic activity grew 0.3 per cent in the December 2011 quarter, unchanged from the previously published figure, SNZ said in a statement.
SNZ said GDP data from the June 1987 quarter to the December 2011 quarter had been updated to incorporate the new industry classification to better represent the current economy.
Westpac economists said the changes meant their understanding of New Zealand's recent economic history had been reset.
In a research note, they said the revisions were probably negative for the inflation outlook and negative for monetary policy.
"However, it is difficult to tell exactly how the Reserve Bank will react," Westpac chief economist Dominick Stephens said.
"The best we can say at this point is that the uncertainly around the (Reserve Bank's) June monetary policy statement has increased considerably," he said.
September 2011 quarterly GDP growth is now estimated as 0.2 per cent, rather than 0.7 per cent.
"It is now clear that the recovery has been slow and that economic activity is still around the 2007 level," he said. "The recovery in private consumption and private investment now looks slower," Stephens said.