Baseball paradox Most baseball hitters perform differently against right-handed and left-handed pitching. Consider two players, Joe and Moe, both of whom bat right-handed. The table below records their performance against right-handed and left-handed pitchers:

(a) Use these data to make a two-way table of player (Joe or Moe) versus outcome (hit or no hit).

(b) Show that Simpson’s paradox holds: one player has a higher overall batting average, but the other player hits better against both left-handed and right-handed pitching.

(c) The manager doesn’t believe that one player can hit better against both left-handers and right-handers yet have a lower overall batting average. Explain in

simple language why this happens to Joe and Moe.

Short Answer

Expert verified

Part (b) The given illustration holds Simpson’s paradox.

Part (c) This could have occurred because Joe has faced more left-handed pitchers than Moe and is able to hit 20%of them, compared to 10%for Moe.

Part (a) The two-way table is


Outcomes
PlayersHitNo Hit
Joe40+80=12060+320=380
Moe120+10=130280+90=370

Step by step solution

01

Part(a) Step 1: Given information

Developing a table based on given information:

PlayerPitcherHitsAt-bats
JoeRight
Left
40
80
100
400
MoeRight
Left
120
0
400
100
02

Part (a) Step 2: Concept

Data concerning two categorical variables are organized in a two-way table of counts. Two-way tables are frequently used to summarize vast volumes of data by categorizing outcomes.

03

Part (a) Step 3: Calculation

We have data on the performance of two players Joe and Moe against right-handed and left-handed pitchers. As per the requirement, consider the above-given table with no hits where no hits is the value obtained by subtracting the number of hits from the number of at-bats.

PlayerPitcherHitsAt-batsNo Hits
JoeRight40100100-40=60

Left80400400-80=320
MoeRight120400400-120=280

Left0100100-10=90

Outcomes
PlayersHitNo Hit
Joe40+80=12060+320=380
Moe120+10=130280+90=370
04

Part (b) Step 1: Calculation

Moe's overall batting average is good in this situation (130 hits for Moe vs. 120 hits for Joe). Joe has faced left-handed pitchers 400 times, while Moe has only faced left-handed pitchers100 times. Joe's share of hits in the left pitcher is defined as 80100=20 percent by definition. The proportion of hits for Moe in the left pitcher is provided as 10100=10 percent by definition. Joe has given up 20% of hits to left-handed pitchers, while Moe has given up 10% of hits to left-handed pitchers. Similarly, we discovered that Joe's proportion of hits is 40100=40 percent, while Moe's proportion of hits is 120400=30 percent for the right pitcher. Simpson's paradox states that when we consider a third variable, the relationship between two category variables can be reversed. We can see from the above that Moe's batting average is good when both pitchers are included, but Joe's batting average is good when both pitchers are considered individually. As a result, the illustration contains Simpson's dilemma. As a result, the graphic depicts Simpson's paradox.

05

Part (c) Step 1: Calculation

The manager does not feel that a single Joe can hit better against both left and right-handed batters while yet having a lower overall batting average. The following information is provided:

This could have occurred because Joe has faced more left-handed pitchers than Moe and is able to hit 20%of them, compared to 10%for Moe. On average, Moe is able to hit 4×10%=40%of his total at-bats (400times)

Joe's right-handed hits are 40%more than Moe's right-handed hits are 30%, while Joe's left-handed hits are 20%more than Moe's left-handed hits are 10%As a result, Joe's average score is lower than Moe's since he has faced the left pitcher 80%of the time whereas Moe has faced the right pitcher 80%of the time.

PlayerPitcherHitsAT-bats% of Hits AT-bats
JoeRight4010040%

Left8040020%
MoeRight12040030%

Left1010010%

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