...at coffee shops:
... [M]en get their coffee 20 seconds earlier than women. (There is also evidence that black people wait longer than white people, the young wait longer than the old, and the ugly wait longer than the beautiful. But these effects are statistically not as persuasive.)
Perhaps, says the sceptic, this is because women order froufrou drinks? Up to a point. The researchers found that men are more likely to order simpler drinks. Yet comparing fancy-drink-ordering men with fancy-drink-ordering women, the longer wait for women remained.
It is also hard to attribute the following finding to a female preference for wet-skinny-soya-machiatto with low carb marshmallows: the delays facing women were longer when the coffee shop staff was all-male, and almost vanished when the serving staff were all-female.
It is not clear whether women were held up by male staff because the men viewed them with contempt, or because male staff flirted furiously. The “contempt” explanation seems more likely, as the extra time that women wait seems to increase when the coffee shop is busy. Who would take extra time out to flirt just when the lines are longer?
Update: Harford has a follow-up post with a response from the study's lead author [Thanks to Sharath Rao for the link].