Parsons, Christopher A.; Sulaeman, Johan; Yates, Michael C. - 2008
for umpires to express such bias.
We collect and analyze every pitch from three complete baseball seasons (2004-2006 … by umpires. To be sure, the time period
2004-2006 is special because only during this time were a portion of the … from
ESPN.com for every MLB game from 2004-2006.2 Our final dataset consists of 2,120,166 total
pitches.3 For each pitch …