A Statistician Reads the Sports Pages: A Historical Tracking of Parity in Baseball

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Notes

¹ I exclude years after 2010 to focus on playoff entry before the introduction of the second wild card spot.

² Payroll data from http://bizofbaseball.com/index.php?option=com_wrapper&view=wrapper&Itemid=186. Playoff data from www.baseball-reference.com/postseason/. Data limitations of this work include the discrepancy between opening day and ending day payroll and the exclusion of the second wild card expansion years (2011–2015).

³ http://mlb.mlb.com/pa/info/history.jsp

⁴ http://static.espn.go.com/mlb/s/2000/1120/891700.html

⁵ For instance, assume there are 30 teams in the league in a given year. For a given year, I rank teams by their opening day payrolls. I assign the highest 10 opening day payroll teams to the top third, the next 10 to the middle third, and the bottom 10 to the lowest third. Within each tercile, I average the 10 opening day payrolls. Figure 1 presents the results from 1969 to 1981. Note that a team is allowed to switch between terciles from year to year. A team that that had the 11th highest opening day payroll in 2000 would be assigned to the middle tier for 2000. If it had the 10th highest opening day payroll in 2001, it would be assigned to the top tier for 2001.

⁶ Figure 2 traces the differences in opening day payroll by tercile across decades. The top-left panel replicates Figure 1, the top right the 1980s, bottom left the 1990s, and bottom right the 2000s.

⁷ http://mlb.mlb.com/pa/info/history.jsp.

⁸ Using the Bureau of Labor Statistics inflation calculator. www.bls.gov/data/inflation_calculator.htm.

⁹ The first year with expanded playoffs was 1995, due to the 1994 baseball strike. Playoffs were previously expanded from two teams to four in 1969. There were also eight spots in 1981, due to a mid-season strike.

¹⁰ cbsprt.co/1RJZRNX.

Additional information

Notes on contributors

Robert A. Nathenson

Robert Nathenson is a postdoctoral researcher and Fellow at the Leonard Davis Institute of Health Economics at the University of Pennsylvania. His research focuses on the application of quantitative methods to the study of health, education, and immigration. He received a PhD in sociology and a master's in applied math and statistics from Johns Hopkins University in 2014.