Note that the author of this piece is female!

Forecasting economic growth, as this essay discusses, is more art than science.  While I don't do a lot of economic forecasting in class, the hemline hypothesis is not one I'd bring up even if I were discussing a macroeconomic forecast.  And the problem with other indicators that might seem more sensible, like the number of cranes one sees in a major metropolitan area, is that when the number is high you are already in the boom.  It doesn't tell you when the boom might end and wasn't all that useful to help you know when the boom would begin.