R: Recipes for Analysis, Visualization and Machine Learning

Performing student's t-test

A one sample t-test enables us to test whether two means are significantly different; a two sample t-test allows us to test whether the means of two independent groups are different. In this recipe, we will discuss how to conduct one sample t-test and two sample t-tests using R.

Getting ready

Ensure that mtcars has already been loaded into a data frame within an R session. As the t.test function originates from the stats package, make sure the library, stats, is loaded.

How to do it...

Perform the following steps:

1. First, we visualize the attribute, mpg, against am using a boxplot:

   > boxplot(mtcars$mpg, mtcars$mpg[mtcars$am==0], ylab = "mpg", names=c("overall","automobile"))
   > abline(h=mean(mtcars$mpg),lwd=2, col="red")