Prepare data
mtcars_data <- mtcars
mtcars_data$am <- as.factor(mtcars_data$am)
Student's t-test, assessing difference in means for two groups
t.test(mpg ~ am, data = mtcars_data) # Assess mpg differences by transmission status (automatic vs. manual)
##
## Welch Two Sample t-test
##
## data: mpg by am
## t = -3.7671, df = 18.332, p-value = 0.001374
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
## -11.280194 -3.209684
## sample estimates:
## mean in group automatic mean in group manual
## 17.14737 24.39231