Hoisted From Comments: Dean Baker on the Auto Sector and Quarterly GDP Estimates

Sounds right to me:

Brad DeLong's Semi-Daily Journal: Now I'm Confused About the Q3 Auto Production Numbers...: Okay, it seems that we have a 3rd quarter problem here. Here's the data for the last 3 years:

2004 Q2 -- -7.1%
2004 Q3 -- 16.6%
2004 Q4 -- 1.9%

2005 Q2 -- -0.7%
2005 Q3 -- 22.6%
2005 Q4 -- -19.1%

2006 Q2 -- -9.4%
2006 Q3 -- 25.7%

So, we seem left with 2 theories. Auto makers have become very pessimistic in the second quarters of the last 3 years, very optimistic in the third, and then very pessimistic again in the 4th, or that BEA has messed up its seasonal adjustment factors. (They assume that automakers will retool in the 3rd quarter and instead they are doing it earlier or later).

I vote for the second theory. The implication is that we overstated growth in the 3rd quarter by somewhere around 0.8 pp (and we did the same last year) and that the BEA numbers will understate true growth in the 4th quarter by perhaps 0.5 pp. Get your recession hats out.