For my bachelor thesis I used an General linear model in SPSS with repeated measures. The data is from a research project on emergent literacy I did with an eye-tracker. The 3 within subject factors are the 3 different distances in which the stimuli were presented. Data entered was their accuracy scores on the different distances.
I used three within subject factors and afterwards I did a second analysis which also included age as a between subject factor.
For the second analysis I was able to report the main effects, but not for the first analysis (the one without the between subject factor). My supervisor gave me the feedback that I need to report if the main effect was significant or not for both analyses.
I tried finding in my output what would be the main effect, but I got tangled in the pillai's trace and greenhouse-geisser. After studying this statistics I was able to make some sense out of it, but it never stated that these would be considered as 'main effects'
Could someone explain to me what the 'main effect' in this analysis means?