However, one unusual economic indicator is signaling that Americans’ confidence in the economy has been rising lately.

Alan Greenspan—who served five terms as Federal Reserve chair between 1987 and 2006—famously uses demand for men’s underwear as an economic bellwether.

The theory is that although underwear is considered a necessity, when economic anxiety is pervasive, men will not replace the pairs that are already in their drawer—causing sales to dip and price inflation to ease. Men are thought to be likely to wait for the economy to bounce back before investing in new pairs of underpants.

“[Greenspan] once told me that if you think about all the garments in the household, the garment that is most private is male underpants because nobody sees it except people, like, in the locker room, and who cares,” NPR correspondent Robert Krulwich said in 2008.

“So he would look [at men’s underpants sales],” Krulwich added. “If you look at the sales of male underpants, it’s just been much a flat line, hardly ever changes. But on those few occasions where it dips, that means that men are so pinched that they are deciding not to replace underpants.”

The so-called men’s underwear index gives credence to Greenspan’s theory—men’s underwear sales in North America fell in 2008 and 2009, amid the global financial crisis.

According to the latest reading of the U.S. consumer price index, men’s underwear prices rose by 5.5% between December and January.

Underwear confidence is rising

Using Greenspan’s theory, the January data suggests that economic confidence drastically turned around last month. The previous two monthly readings, for November and December, showed negative inter-month growth in the price of men’s underpants.

The increasing price of the garments aligns with other signs that suggest a positive shift in economic outlook might be underway.

Consumer sentiment in the U.S. has staged a bumpy recovery in recent months, after plummeting last summer to its lowest since the 2008 financial crisis, according to the University of Michigan’s monthly reading.

Sentiment is still far below pre-pandemic levels, but rose to its highest level in almost a year in January alongside apparent rising demand for men’s underwear.

A separate reading of U.S. consumer confidence has followed a similar trajectory.

Preliminary data for this month, which is due to be finalized next week, suggests U.S. consumer sentiment is continuing to improve.

As consumer sentiment reached its lowest levels last year, men’s underwear prices stagnated and then fell, official data showed.

At the time, around 90% of Americans polled by the American Psychiatric Association said they were anxious or very anxious about inflation.

A detailed breakdown of individual items’ prices in the most recent CPI report showed that men’s underwear experienced one of the biggest price increases across the board in January. Eggs and condiments also saw their prices surge, recording monthly cost increases of 8.5% and 6.2%, respectively.

Greenspan isn’t alone in monitoring a specific—and somewhat unusual—item in a search for clues about the economy. Big Macs, frozen lasagna, and lipstick have all been used to measure the state of the economy.