R Statistics Cookbook

How to do it...

In this example, we will use the very famous iris dataset, which contains 50 observations for 3 flower species (there are three species: Iris setosa, Iris virginica, and Iris versicolor). There are four measurements for each observation: the length and width of the sepals and petals. Let's get started:

1. First, we do our test. The formula here needs to specify all of the variables separated by | and, after that, the group type specified by ~. Actually, this function will return four different statistics, calculated using two different p-values (the standard ones and the permutation ones—the latter are more precise). This actually leads to 4 x 2 = 8 p-values. In this case, all the statistics agree that there are differences ...