How many marketing scientists does it take to forecast a crew shirt?

I just returned from the INFORMS Marketing Science Conference. This was 3 days of listening to mathematical models of demand, supply, forecasting, logistics, optimal product assortment, and similar topics. Registrants received a souvenir crew-neck shirt.

With 700+ "marketing scientists" at a conference, you wouldn't think that the conference would misforecast the number of souvenir shirts of various sizes required so badly. There were plenty of XL's, but no S or M's at all. Evidently, they thought this group of academics would be wearing the shirts around their egos, not their torsos.

This entry is a bit unfair. The hosts at the University of Pittsburgh did a fine job organizing the conference, and this was the only glitch I saw.