The Formula for the Donovan Index is a simple mathematical equation that accurately determines the rate at which cities' teams, and by extension cities, win championships in major sports leagues. The equation for a team (we'll use the 76ers) would be as follows:
Sum of the number of teams in NBA in 76ers' championship seasons
Number of Seasons that the 76ers have played
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Lets make our example concrete. Since entering the NBA in 1963-64, the Philadelphia 76ers have won the NBA title twice, in 1967 and 1983. The two championships are not equal, however. In 1967, the NBA had 10 teams; in 1983, it had 23. This discrepancy is known as the "Riordan Factor". We thus award the 76ers 10 points for their first championship and 23 for their second. We determine their index score by adding 10 to 23 and dividing the sum by 44 seasons:
10 + 23
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= | 0.75 |
It thus follows that an "average" score is 1.00. In a ten-team league, a team should win once every ten years. Ten teams divided by ten seasons equals one. The 76ers score a 0.75; they don't quite win titles at an average rate. The city of Philadelphia scores a 0.69. It's that simple.
