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What’s more improbable: OSU/Florida or Oster/Levin?

It is a strange coincidence that Ohio State and Florida played for the national championship in both college football and basketball this year. What are the odds of something like this happening in the two premier sports? Let’s assume (1) there are 50 universities that have a shot at winning each of these national titles, (2) all 50 of these universities have an equal chance of making it to the final game.

I’m not trying to compute the odds that these two particular universities make it to the finals of both events — just that the same two teams make it. So any two teams can make the final game in football, I just need to figure out what the chances are they also make it in basketball. The odds that the first team will make it are 1 in 25 — there are two slots and 50 teams competing for the slots. But if Ohio State makes it, then there is only one slot left for Florida (with 49 teams competing for the spot), so the chances for Florida conditional on Ohio State already making it are 1 in 49. So the likelihood of the same two teams making it in both sports under my set of stylized assumptions (assuming I did the statistics right which is no doubt the biggest assumption of all in this calculation!) is about 1 in 1,225. So this sort of thing happening is a once-a-millennium kind of event if my assumptions are realistic.

That coincidence, however, is nothing compared to the next one. My favorite source of interesting facts has recently become the Everit St. Weekly. Last week I learned from this reliable source that Emily Oster is a liar. Now, reading further, I discover that two of the best young economists in the entire world, Emily Oster and Jon Levin, grew up on the same block. Now what are the odds of that?

Levin and Oster are easily among the 50 best young economists in the world. I don’t know exactly how many blocks there are in the United States. There are about 10,000 in Chicago. Chicago has about 1 percent of the U.S. population. So if Chicago blocks have an average number of people per block, then that would mean there are about 1 million blocks in the United States. My guess is there are more people per block in Chicago than for the country on average, so let’s say 2 million blocks in America. (That works out to 150 people per block, which doesn’t seem crazy.)

So under the extreme assumptions that (1) all blocks have 150 people, and (2) all blocks have an equal probability of producing a top economist, the odds that you pick a random block and it turns out that two kids growing up on Everit St. would become top economists is about 1.6 billion to 1. Under these assumptions, the chance of any block in America yielding two top economists would be roughly 40,000 to 1.

Was it something in the water on Everit Street? Probably not. By far the strongest predictor of getting a Ph.D. in economics these days is having a parent who is a professional economist. This is just a partial list, but off the top of my head I can think of the following economists whose children got/will get a Ph.D within a five year period: George Akerlof/ Janet Yellen, Ben Friedman, Richard Levin, Rob Townsend, Francine Blau/Lawrence Kahn, and Lawrence Ianoconne. That is just the tip of the iceberg — I know there are many others as well. So if you start with a block that has three families headed by economists (as Everit Street had since Bob Shiller’s family lived on that block as well), the odds start looking a lot more like Ohio State vs. Florida.

Be sure to stay tuned for the next gripping installment of my analysis of the Everit St. Weekly.