Conducting a one-way ANOVA
Analysis of variance (ANOVA) investigates the relationship between categorical independent variables and continuous dependent variables. It can be used to test whether the means of several groups are equal. If there is only one categorical variable as an independent variable, you can perform a one-way ANOVA. On the other hand, if there are more than two categorical variables, you should perform a two-way ANOVA. In this recipe, we discuss how to conduct a one-way ANOVA with R.
Getting ready
Ensure that mtcars
has already been loaded into a DataFrame within an R session. Since the oneway.test
and TukeyHSD
functions originated from the stats
package, make sure the library, stats
, is loaded.
How to do it...
Perform the following steps:
- We begin exploring by visualizing the data with a boxplot:
> boxplot(mtcars$mpg~factor(mtcars$gear),xlab='gear',ylab='mpg')

Comparison of mpg of different numbers of forward gears
- To visualize how
gear
andmpg
is related, a dot plot...