My data follow this outline:
IV1 IV2 IV3 IV4 RV 1 1 0.5 B 5.3 2 2 1 U 15.3 2 1 0.5 A 51.3 3 3 2 B 5.35
- IV1 has 3 levels: 1, 2 and 0.5
- IV2 has 3 levels: 1, 2 and 0.5
- IV3 has 3 levels: 1, 2 and 3
- IV4 has 3 levels: B, U, R, S, A
All of them are categorical. The response variable is times measured in seconds.
Due to the non-normality of the data and the heteroscedasticity I cannot use Analysis of Variance (ANOVA). I have tried five data transformations to see if I can apply ANOVA (square-root, 2-power, e-power, log, ln). None of these fixes the data so that they pass either visual exploration or Levene and Kolmogorov's tests. Non-parametric test (distribution-free) like Kruskal-Wallis or Freidman cannot handle factor interaction as can ANOVA.
What can I do?