I am analyzing data from a sport psychology experiment I conducted on Motor Imagery. My two treatments are movement and perspective, which led to a 2 x 2 design. My goal was to see if, over 4 trials, dart-throwing scores would be different across groups. I opted for a MANCOVA with the four trials as within factor, movement and perspective as between factors, and an initial trial (Assessment Trial) as a covariate, to take into account their ability.
My supervisor suggested to also look at nonparametric ways of looking at my data. However, all the methods I have found only involve differences between two repeated measures (sign test, or Wilcoxon Signed-Ranks test).
Do you have any suggestion as of how I could rethink of my data to attempt nonparametric analyses?