The Friday File: In 1926, economist George Taylor articulated the Hemline Index. It suggests women wear shorter outfits in good times, longer ones in bad. Thus, the popularity of maxi dresses is terribly troubling. Fortunately, researchers have found that while hemlines are correlated with GDP growth, it’s with a three year lag, meaning today’s fashions reflect economic growth in 2012. Regrettably, GDP growth today is the same as in 2012.