Best economic metric based on a Seinfeld routine

The joke about men keeping underwear until it broke down into individual underwear molecules came to mind while I was listening to an entertaining piece on alternative economic indicators (via the good people at Marketplce). The list included Marine retention and abandoned pets and, of course, this:

Ryssdal: I'm just looking at the list of things we were going to talk about and I see next -- and I hesitate to mention this -- the men's underwear index.

Brancaccio: The theory is during bad times we're less likely to replace our boxers and our briefs. I wouldn't have brought the tone of this conversation down this far if the source had not been so exalted.

Ryssdal: Give it up. Who is it?

Brancaccio: Well, back in the '70s before he was Fed Chairman, Alan Greenspan ran his consulting firm. One way he kept track of the economy was by looking at offbeat economic indicators like the men's underwear indicator -- MUI for those of you in the know. Here's the theory: When you're feeling strapped for cash, your less likely to replace your undergarments even though most people see under see underwear as a necessity not a luxury.

Ryssdal: So one is obliged to ask David, how are sales now?

Brancaccio: Well, we did check. And according to an analyst who tracks these things -- underwear sales for the NPD Group -- sales, currently, are up 5.2 percent.