To open R with the data set preloaded, right-click here and choose "Save Target As" to download the file to your computer. Then find the downloaded file and double-click it to open it in R.
The data have been loaded into the data frame drinks
. Enter the command drinks
to see the data. The variable in the data frame is drinks.per.week
.
To use R to perform a t-test for the population mean using our data and the designated alternate hypotheses, enter the command:
t.test(drinks$drinks.per.week,mu = 4.73, alternative = "two.sided")
R returns all the information you need to complete your t-test, including:
Note: Using R, the possible values for the alternative hypothesis are "less"
, "greater"
, and "two.sided"
, corresponding to the three types of alternative hypotheses in a t-test. If "two.sided"
is the alternative, then the appropriate confidence interval is returned. If "less"
or "greater"
is the alternative, then the returned confidence interval is what is known as a one-sided confidence interval, which we have not discussed.