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CHAPTER 1
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DO CATCHERS WEAR OUT?
A common claim in baseball is that catchers tend to wear down as the season progresses
because of the physical demands of the position. This claim seems to have even more validity
for catchers who rarely get time off and who play in warm, humid climates. In 1996, Ivan
Rodriguez of the Texas Rangers exemplified these conditions. He played in 153 of his team’s
162 games (a very high proportion for a catcher), and the heat and humidity in the Dallas area
can be extremely high for weeks at a time. It would seem reasonable to expect that his ABILITY
to hit would decrease toward the end of such a physically challenging season. During the
season’s first five months (April-August), Ivan Rodriguez had a batting average of 0.317 (170
hits in 536 at-bats), but in the last month of the season (September) his batting average was
only 0.214 (22 hits in 103 at-bats).
1) Make a bar chart to compare Rodriguez’s PERFORMANCES in the first five months with the
last month of the 1996 season. Briefly describe what you see.
2) Suppose that Rodriguez’s ABILITY to get a hit in 1996 is actually 0.317. Explain what ABILITY
means in this context.
3) Assuming that Rodriguez’s ABILITY to get a hit is 0.317, describe how to use a spinner to
simulate the number of hits he gets in 103 September at-bats.
4) One hundred trials of the simulation described in #3 were carried out and the number of hits
was recorded for each trial. These results are shown in the dotplot below.
Based on the results of the simulation, does Rodriguez’s actual PERFORMANCE of 22 hits in 103
at-bats provide convincing evidence that his ABILITY to get hits decreased in September?
Explain.
5) If we conclude that his ABILITY did go down in September, can we say that the wear-and-tear
of the season is the cause of the decline? Explain.