I tried to perform a robust mixed anova in R because the assumptions of homoscedasticity, normal distribution, and equality of covariances were violated. I have one between subject factor (group) and one within subject factor (situation). I have two questions in total.
Question 1: How do I get the corresponding effect sizes?
mixedanova <- WRS2::bwtrim(formula = value ~ group*situation, id = id, data = data.long)
Output:
| value | df1 | df2 | p-value | |
|---|---|---|---|---|
| group | 162.9427 | 2 | 33.9744 | 0 |
| situation | 136.4997 | 1 | 38.5618 | 0 |
| group:situation | 61.4333 | 2 | 28.2040 | 0 |
Question 2: How do I interpret the post hoc tests? (Why are there values greater than 1?) (Why does the output not change when I change nboot?)
sppba(formula = value ~ group*situation, id = id, data = data.long, est = "mom", nboot = 500)
Test statistics:
Test whether the corrresponding population parameters are the same:
p-value: 0
| group | Estimate<dbl> |
|---|---|
| 1-2 | 0.8178253 |
| 1-3 | 1.4685165 |
| 2-3 | 0.6506912 |
sppbb(formula = value ~ group * situation, id = id, data = data.long, est = "mom", nboot = 500)
Test statistics:
Test whether the corrresponding population parameters are the same:
p-value: 0
| Estimate<dbl> | |
|---|---|
| situation 1-situation 2 | 0.2575347 |
sppbi(formula = value ~ group * situation, id = id, data = data.long, est = "mom", nboot = 500)
Test statistics:
Test whether the corrresponding population parameters are the same:
p-value: 0
| header 1 | header 2 |
|---|---|
| situation1-situation2 1-2 | -0.58068783 |
| situation1-situation2 1-3 | 0.07747543 |
| situation1-situation2 2-3 | 0.65816327 |
Thanks for your help in advance!!
I have read through the paper by Mair & Wilcox (2020) "Robust Statistical Methods Using WRS2" and have tried varying the functions bwtrim, sppba, sppbb, and sppbi, but unfortunately without success.