We can observe the contents of the vector groups simply by typing groups +. Now, on this vector in which are stored all the data, we create the 4 levels: Now we combine the 4 vectors in a single vector:
The software R provides two tests: the Bartlett test, and the Fligner-Killeen test.
To proceed with the verification ANOVA, we must first verify the homoskedasticity (ie test for homogeneity of variances).
