Selection bias, for those unfamiliar with the concept, occurs when a particular, non-random part of a population is sampled. We normally think of selection bias as occurring in statistical analyses, but it happens other places as well. Take newspaper interviews:
The owner of the Hilltop Carry Out pizzeria and Skybox Bar and Grill in South Baltimore, Giorgakis has seen his restaurants much busier on game days this season than in seasons past. He has had to bring in an extra cook to handle the pre-game and post-game rushes at the pizzeria, and he has noticed that the crowds have been lingering longer at his bar on game days.
...Sporting stores are selling more hats and jerseys. Sports bars are staying busier longer on game days, and party platters have been a hot seller at supermarkets. Media companies are getting a lift. Even the Maryland Lottery is selling more tickets.
Denise Gendimenico can feel the difference in her tips. A waitress at the Silver Spring Mining Company in Perry Hall, which offers discount food and drinks during all Ravens and Terps games, Gendimenico has noticed that a winning home team makes for a happier customer.
"They're pumped up and they're a little bit more willing to spend money and stay longer," she said. "It definitely makes a difference."
"The bars have been absolutely packed," said Keith Kujawa, general manager for the Silver Spring Mining Company restaurants in Perry Hall, Bel Air and Hunt Valley. "They're usually pretty busy, we have a pretty good fan club, but a lot of the fair-weather fans, they're all coming out. ... We're getting new faces."
All the fans have been enough for Domino's to hire extra workers for game days. Kris Schutz, corporate regional manager for Domino's in Baltimore City and Baltimore County, said he has hired two extra employees at each of the eight local stores he manages to handle the football rush. And sales go up about 20 percent during game time, an increase reminiscent of the Ravens' Super Bowl season, he said.
Eddie's of Roland Park stocks shelves at its two stores with wings and veggie and cheese trays on game days. Employees put out plenty of crab dip, take orders for super-size subs and dole out advice on how to make chili with beef from the butcher counter, said Jo Alexander, communications director for the supermarkets, one on Roland Avenue in North Baltimore and one on North Charles Street in Baltimore County.
Of course you'll get comments about how great things are when you interview bar owners, waitresses, and the like when the team is winning.
Perhaps I'm being too harsh. There is the following, given almost as an aside, buried deep in the bowels of the article:
Sports economists caution that it's more a matter of some businesses reaping the benefits than an overall economic boost. That's because fans are spending money on Ravens-related activities instead of on something else, such as going to a movie.
Yes, that's part of what's going on. In addition, more money leaks out of an economy when it's spent on sports. But this passage is almost like the town of population 60 on a long stretch of highway. If you blink, you'll miss it. After all, we do not want rain on the parade.
HT Dennis Coates at TSE.