Using Rstudio, how do I calculate 2 new variables (1.homeruns per at bat before
ID: 3048958 • Letter: U
Question
Using Rstudio, how do I calculate 2 new variables (1.homeruns per at bat before steroids 2. homeruns per at bat with steroids) and use a paired t-test to determine to determine if there was a difference between steroid and non steroid homerun hitting?
Player
HomeRunsBefore
AtBatsBefore
HomeRunsAfter
AtBatsAfter
J. Bagwell
140
3095
306
4602
B. Bonds
504
7725
258
2122
J. Canseco
90
1815
551
8553
M. Maguire
338
4194
245
1993
D. Ortiz
141
2952
279
3878
R. Palmeiro
196
5222
373
1410
A. Rodriguez
193
3696
545
5966
I. Rodriguez
149
6162
162
3430
S. Sosa
107
2563
502
6250
Player
HomeRunsBefore
AtBatsBefore
HomeRunsAfter
AtBatsAfter
J. Bagwell
140
3095
306
4602
B. Bonds
504
7725
258
2122
J. Canseco
90
1815
551
8553
M. Maguire
338
4194
245
1993
D. Ortiz
141
2952
279
3878
R. Palmeiro
196
5222
373
1410
A. Rodriguez
193
3696
545
5966
I. Rodriguez
149
6162
162
3430
S. Sosa
107
2563
502
6250
Explanation / Answer
Save the data as player.csv and load the file in RStudio with the below commands.
> player = read.csv("player.csv", header = TRUE)
> player
Player HomeRunsBefore AtBatsBefore HomeRunsAfter AtBatsAfter
1 J.Bagwell 140 3095 306 4602
2 B.Bonds 504 7725 258 2122
3 J.Canseco 90 1815 551 8553
4 M.Maguire 338 4194 245 1993
5 D.Ortiz 141 2952 279 3878
6 R.Palmeiro 196 5222 373 1410
7 A.Rodriguez 193 3696 545 5966
8 I.Rodriguez 149 6162 162 3430
9 S.Sosa 107 2563 502 6250
1. homeruns per at bat before steroids is calculated as
> HomeRunsPerAtbat.Before = player$HomeRunsBefore / player$AtBatsBefore
> HomeRunsPerAtbat.After = player$HomeRunsAfter / player$AtBatsAfter
> HomeRunsPerAtbat.Before
[1] 0.04523425 0.06524272 0.04958678 0.08059132 0.04776423 0.03753351 0.05221861 0.02418046 0.04174795
> HomeRunsPerAtbat.After
[1] 0.06649283 0.12158341 0.06442184 0.12293026 0.07194430 0.26453901 0.09135099 0.04723032 0.08032000
Paired t-test to determine if there was a difference between steroid and non steroid homerun hitting is done by the below command.
> t.test(HomeRunsPerAtbat.Before,HomeRunsPerAtbat.After)
Welch Two Sample t-test
data: HomeRunsPerAtbat.Before and HomeRunsPerAtbat.After
t = -2.4029, df = 8.9678, p-value = 0.0398
alternative hypothesis: true difference in means is not equal to 0
95 percent confidence interval:
-0.105018871 -0.003139601
sample estimates:
mean of x mean of y
0.04934443 0.10342366
The p-value of the test is 0.0398 which is less than the significance level of 0.05. So, we reject the null hypothesis and conclude that there was significant difference between steroid and non steroid homerun hitting
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