Business Insider- Chiwoong Lee at Goldman Sachs has a new report out (“China vs. 1970s Japan”, September 25, 2012) in which he predicts that China’s long-term growth rate will drop to 7.5-8.5%. I disagree very strongly with his forecast, of course, and expect China’s growth rate over the next decade to average less than half that number, but the point of bringing up his report is not to disagree with the details of his analysis.

I want instead to use his report to illustrate what I believe is a much more fundamental problem with these kinds of research pieces on China. The mistake I will argue he is making is one that is fairly common. It involves determining the past relationship between certain inputs and the outputs we want to forecast – say GDP growth. Once these are determined, the economist will carefully study the expected changes in the inputs, and then calculate the expected changes in the outputs, to arrive at his growth forecast.

Read more: http://www.mpettis.com/2012/10/27/when-the-growth-model-changes-abandon-the-correlations/#ixzz2Ai8rHrUD