Table 1

Illustration of Simpson's paradox using batting averages for two prominent baseball players

N hitsN at-batsBatting averageN hitsN at-batsBatting averageN hitsN at-batsBatting average
Derek Jeter12480.2501835820.3141956300.310
David Justice1044110.253451400.3211495510.270
  • Example taken from Reference 11; statistics confirmed through (last accessed 25 Jun 2014). The example shows that David Justice had a higher batting average (the ratio of hits over ‘at-bats’) than Derek Jeter in both 1995 and 1996. Yet, when the 2 years are combined, Derek Jeter has the higher batting average. This paradoxical reversal of their batting averages results from the large difference in ‘at-bats’ in the 2 years.