GDP Growth Rates Need Their Time Periods Attached

Econbrowser reports an Atlanta Fed GDPNow estimate of 5.1 percent annualized quarter-over-quarter growth for the third quarter. In the same post, the FT-Booth forecast is 2 percent fourth-quarter-over-fourth-quarter growth.

Those labels matter. The first describes a quarter's growth expressed at an annual rate; the second compares the fourth quarter with the fourth quarter a year earlier. They are not two directly comparable estimates of the same span.

Econbrowser also places GDPNow above the other nowcasts it charts. That reported disagreement is worth distinguishing from the tempting 5.1-versus-2 comparison: before treating a gap as a dispute about the economy, check that both numbers measure growth over the same period.