It seems the folks reporting on the third quarter GDP forgot to do their homework. The articles touted the 3.0 percent growth figure, which was somewhat stronger than generally expected. However much of the basis for this stronger than expected growth was a pick-up in inventory accumulations that added 0.73 percentage points to the growth rate in the quarter. The growth in final demand was just 2.3 percent.

It is common to look at final demand growth, which excludes inventory changes, both because the inventory numbers are highly erratic and also are not sustainable. No one thinks that the pace of inventory accumulation will continue to increase at anything like the pace in the third quarter. This point is important, since if we are trying to determine the underlying growth path of the economy, it is far more likely to reflect the rate of growth of final demand than a GDP number that is inflated (or deflated) by big changes in inventories.

One potentially very important item that seems to have been missed in the coverage of third quarter GDP was the pick-up in productivity growth implied by the GDP data. Output in the non-farm business sector rose at a 3.8 percent rate in the quarter. With hours worked in the private sector increasing by less than 1.0 percent, this likely means a rate of productivity growth close to 3.0 percent. This would be a huge uptick from the 0.7 percent rate we have seen the last five years.

Productivity data is highly erratic so a single quarter’s data should always be viewed cautiously. But an uptick in productivity growth has to start somewhere and if this is the first sign, it is a really huge deal. More rapid trend productivity growth would be far more important than whether the GDP growth rate in the quarter was 3.0 percent or 2.0 percent.