A Different Measure of Diversity in Pro Sports

By Henry Johnson

On June 24, The Institute for Diversity and Ethics in Sport (TIDE) released its evaluation of the NBA in terms of racial and gender hiring practices for executives, referees, announcers, coaches, and players. The league earned a grade of “A+” from TIDE, as 80.5% of players and 43.3% of coaches during the 2013-2014 season were people of color.

While the NBA has done a fantastic job in providing opportunities to women and minorities in a once white-male dominated industry, it hasn’t necessarily achieved literal diversity. There are signs suggesting that diversity could be a precious commodity in sports. An analysis of TV viewer demographics in The Atlantic seems to indicate a correlation between players’ and fans’ racial composition; as American sports leagues compete with each other for ratings, having strong player diversity that appeals to a wide array of viewers will translate to enormous gains in TV revenue down the line.

So here, I will measure diversity in a more literal way using Simpson’s Index, developed by ecologists to measure biodiversity. In the context of sports, a league’s diversity score is equal to the probability that two players drawn at random will be of different races or ethnicities. The higher the score, the more diverse a league is. In terms of interpretation, Simpson’s Index is very similar to the USA Today Diversity Index, which has been used to look at racial and ethnic spread across the country.

Simpson Index Applied to American Sports Leagues
Simpson Index Applied to American Sports Leagues

We can also use TIDE’s data on the MLB, MLS, NFL, and WNBA to see which leagues are most diverse according to this metric. (Note that our categories will be the same as TIDE’s: White, African-American, Latino, Asian, and Other.) According to Simpson’s Index, the NBA is lacking in diversity relative to other leagues; in fact, there’s about a 66% chance that two randomly drawn NBA players will be of the same race (including a 58% chance two randomly drawn players are both African-American). Two randomly drawn MLS players, by contrast, have only about a 32% chance of belonging to the same race. The MLS is also the only league in which no single race represents a majority of players.*

Racial Breakdown of Five American Sports Leagues
Racial Breakdown of Five American Sports Leagues

Second to the MLS is the MLB, with an index of 0.542. This is largely driven by the presence of international players from Latin American and Asian countries. The league appears eager to diversify further by recruiting more African-American ballplayers, an effort which is reflected in programs like Reviving Baseball in Inner Cities, or RBI. According to TIDE, African-Americans make up just 8.2% of major league rosters this season.

The third and fourth most diverse leagues are the NFL and WNBA, which had Simpson’s Indices of .469 and .425, respectively. Like the NBA, these leagues are dominated by two races. In fact, in the three leagues that Simpson’s Index identifies as the least diverse, over 90% of players fall into two racial categories: Black and White.

The ways in which diversity affects sports clubs warrant further exploration. There are indications, though, that it may have beneficial impacts: Recently, a trio of professors found a positive link between winning percentage and linguistic diversity of soccer teams. Whether an analysis of racial diversity would yield similar results may be a topic for future research.


*The MLS’ diversity score is aided by the high number of players in the “Other” category. If every single “Other” player were White, the league’s Simpson’s Index would dip to .522, just below the MLB. But TIDE explains that “this dramatic change [in “Other”] is because in the previous RGRC an international player who was Black was counted as an African-American.” So unless more than 73 of the 89 soccer players listed as “Other” are White, the MLS remains the most diverse as per the index

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