I have conducted a within-subject user study. Each user works with 3 user interfaces and reads a couple of tweets in each UI and we record how many milliseconds they spend on reading each tweet/comment for each UI
I was doing ANOVA to see if the type of UI contributes to the amount of time people spend on each UI. Everything was shiny until I noticed that the dataset fails on Bartlett's test with a very low p-value. I used an "ANOVA on Ranks" instead (ranked the timing values and ran ANOVA again) of ANOVA there and everything became shiny again!
My question is:
- Can I use "ANOVA on Ranks" when there is no homogeneity of variances. Do I need to do a transformation? or use a Friedman test instead?
- The more important question is what should I use as the follow up method (since I cannot use any t-test type test)
Thanks a lot for the help