This function takes a variable and a grouping variable as arguments, and returns a statistcal test to use, expressed as a single-term formula.
tests_auto(var, grp)A statistical test function
The variable to test
The variable for the groups
This function uses appropriate non-parametric tests depending on the number of levels (wilcoxon.test for two levels and kruskal.test for more), and fisher.test with fallback on chisq.test on error for factors.