Are men buying briefs and boxers? What skirt length are women wearing? Believe it or not, these are two quirky trends, among many, that can predict an economic downturn.

Tracking the performance of men’s underwear sales is something that interests Alan Greenspan, former chair of the Federal Reserve. Greenspan believes men’s underwear sales dip during economic hardship and rise when the economy performs well. To track this, there’s even a men’s underwear index, and economists seek to find correlations between economic booms and busts.

The index confirms Greenspan’s theory, as during The Great Recession of 2008, men’s underwear sales dropped significantly, but recovered at the same time as the national economy did in 2010, per CNN.

The index is used as a barometer for consumer discretionary spending, and while it may certainly be the weirdest index to read the economic tea leaves, it is not the only one.

Hemline Index

In another sign of consumer spending predicting the state of the economy, the hemline index is sometimes used. The hemline index says that the higher the hemline, the stronger the economy, such as in the 1920s and the 1960s, but lower hemlines on skirts mean a badly performing economy.

Sonnet Stanfil, fashion curator at London’s Victoria & Albert Museum, confirmed this, telling The Daily Express in February 2008, “[The 1920s] spelled economic freedom. Women threw off the shackles of the heavily corseted Edwardian period, and hemlines became dramatically shorter for the first time.” Then, following the 1929 crash and the Great Depression, longer skirts were back in vogue.

The theory, while unproven, is believed by some to have predicted periods of stability and hardship. Hemlines also rose during the World War II boom, but fell just before the recession of 1949. Decades later, skirt lengths rose during the 1980s, only for longer skirts to come into fashion right before the 1987 market crash.

Lipstick Index

Finally, the lipstick index, coined by Estee Lauder Chairman Leonard Lauder, was used to describe an uptick in cosmetic sales during the early 2000s recession. Leonard Lauder claimed rising lipstick sales across Estee Lauder brands could be an indicator of a recession, and, in fact, the index rose during a brief recession in 1990-91.