The Hemline Index is a theory presented by economist George Taylor in 1926.
Recent research suggests it is valid. The theory suggests that hemlines on women's dresses rise along with stock prices. In good economies, we get such results as miniskirts (as seen in the 1960s), or in poor economic times, as shown by the 1929 Wall Street Crash, hems can drop almost overnight. Desmond Morris revisited the theory in his book The Naked Ape and the theory was also the topic of a question on the BBC Panel Show QI in 2010.