For N.B.A. Hopefuls, Zip Code Matters

(Photo: Keith Allison)

(Photo: Keith Allison)

We’ve blogged before about the (relatively small) effect of birth month on athletic excellence.  But how does birth location affect a potential athlete? In The New York TimesSeth Stephens-Davidowitz  calculated the probability of getting to the N.B.A. by Zip codeHe found that players like LeBron James, born to a low-income teenage mom, are the exceptions to the rule:

I recently calculated the probability of reaching the N.B.A., by race, in every county in the United States. I got data on births from the Centers for Disease Control and Prevention; data on basketball players from; and per capita income from the census. The results? Growing up in a wealthier neighborhood is a major, positive predictor of reaching the N.B.A. for both black and white men. Is this driven by sons of N.B.A. players like the Warriors’ brilliant Stephen Curry? Nope. Take them out and the result is similar.

But this tells us only where N.B.A. players began life. Can we learn more about their individual backgrounds? In the 1980s, when the majority of current N.B.A. players were born, about 25 percent of African-Americans were born to mothers under age 20; 60 percent were born to unwed mothers. I did an exhaustive search for information on the parents of the 100 top-scoring black players born in the 1980s, relying on news stories, social networks and public records. Putting all the information together, my best guess is that black N.B.A. players are about 30 percent less likely than the average black male to be born to an unmarried mother and a teenage mother.

Stephens-Davidowitz also notes that, not surprisingly, height matters. He speculates that the N.B.A is becoming more international because foreign countries, particularly those that have increased greatly in wealth and early life conditions, are producing taller men.



What does grow up in mean? I mean James went to a wealthy high school, but by that point he was already a highly recruited basketball star. So when does it matter to "grow up"? The early years?

Some of these guys really bounced around.


No attempt to address the endogeneity here?


Nutrition. being born in a wealthier family means you eat better and healthier in the first years of your life, meaning better skeleton structure, musculature and fat/muscle ratio.

Potential athletes born in wealthier neighbourhoods are less likely to get into drugs, gangs and other things in their early teens derailing their potential career.

Also, despite all the playground mythology in the movies, I suspect kids born in wealthier areas go to better schools where they get better trainers and a talent can be noted and built at an earlier stage.

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Also, if you're wealthier, you probably have more playgrounds and more opportunity to spend time at them (a nanny to take you there, or to basketball camp, at a young age), or even your own regulation basketball hoop at home. You also have more time for practice, since nobody's encouraging you to get a job to help out with the family's expenses.


One big factor left off is that almost all NBA players(except for a very few straight from high school players like LeBron) had to play NCAA Div I or Div II college basketball to gain the exposure to even get a shot at the NBA. There are minimum GPA and test score requirements that cut off the bottom tier of young men. While talented athletes might me graded rather leniently, they at least have to generally show up and not drop out of high school or college. Minimum SAT/ACT scores can be a reach for some players from the poorest environments.

Also while the study controlled for NBA fathers, it did not control for parents who played college basketball. More than 10 times as many mens high school basketball players go on to play NCAA college basketball for every player that even gets a cup of coffee in the NBA. The handful of NBA players from my area all had parents who were star athletes ~25-30 years ago, but those parents all topped out at being a decent starter for a good Div I school or an all-conference player at a lower level school. So their parents got the benefits of at least a few years of higher education, and all it took was growing a few inches taller or having a few basketball skills that developed a shade better to make it a step beyond their parents made it.


Gabe only has place of birth and high school. The first one tells you where the hospital is located, the second tells you which prep school recruited them and gave them an athletic scholarship.