  Box score statistics in the National Basketball Association are used to
measure and evaluate player performance. Some of these statistics are
subjective in nature and since box score statistics are recorded by
scorekeepers hired by the home team for each game, there exists potential for
inconsistency and bias. These inconsistencies can have far reaching
consequences, particularly with the rise in popularity of daily fantasy sports.
Using box score data, we estimate models able to quantify both the bias and the
generosity of each scorekeeper for two of the most subjective statistics:
assists and blocks. We then use optical player tracking data for the 2014-2015
season to improve the assist model by including other contextual
spatio-temporal variables such as time of possession, player locations, and
distance traveled. From this model, we present results measuring the impact of
the scorekeeper and of the other contextual variables on the probability of a
pass being recorded as an assist. Results for adjusting season assist totals to
remove scorekeeper influence are also presented.
