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Simpson's paradox: the better hitter with the worse average

simpsons-paradoxconfoundingaggregation

Two hitters are compared by batting average (hits / at-bats), split by the handedness of the pitcher they faced:

vs RHPvs LHPSeason
Player X35/100 (.350)100/400 (.250)135/500 (.270)
Player Y136/400 (.340)24/100 (.240)160/500 (.320)

X hits better against right-handers (.350 vs .340) and against left-handers (.250 vs .240), yet Y's overall average is higher (.320 vs .270).

Who is the better hitter, and explain the reversal.

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