A Comparing groups
A.1 Comparing two unpaired groups
Assumption  Test  Function  Effect size  Function 

Parametric  TTest Welch TTest 

Cohen’s d  cohens_d() 
Nonparametric  MannWhitney U  wilcox.test(paired = FALSE) 
Rankbiserial r or Wilcoxon R 
or

A.2 Comparing two paired groups
Assumption  Test  Function for test  Effect size  Function for effect size 

Parametric  TTest  t.test(paired = TRUE) 
Cohen’s d  cohens_d() 
Nonparametric  Wilcoxon Signed Rank Test  wilcox.test(paired = TRUE) 
Rank biserial r or Wilcoxon r 
or

A.3 Comparing multiple unpaired groups
Assumption  Test  Function for test  Effect size  Function for effect size 

Parametric  ANOVA 

Epsilon squared  eta_squared() 
Nonparametric  KruskallWallis test  kruskal.test() 
Epsilon squared (rank)  rank_epsilon_squared() 