Repeated measures study with a covariate

We conducted a study where we are measuring perceived tiredness at different intervals (a total of 10). We recorded a score before starting the experiment, as a covariate to account for differences in baseline (i.e. different people would have started at different levels of tiredness).

The experiment asked them to do a single task (keep pressing a button occurring at a random location on a smartphone). After every 1 minute, the activity (smartphone app) paused, and the participants were asked to give a score between 0-10 for their perceived tiredness. The activity ran for 10 minutes and thus we have 10 scores for each subject (plus 1 for the baseline).

I want to compare the effect of the condition (treatment) between all the participants (within-subject).

Now, ANCOVA is good for adjusting pre-treatment scores (i.e. baseline) and any variations that might come due to participants starting at different levels of tiredness.

However, ANCOVA is generally good for comparison between groups. I only have one group and everyone is doing the same tasks. I can treat every participant as a group (since I want to compare within participants), and run ANCOVA but I am not convinced this is the right approach.

Suggestions?

• What do you mean that you "want to compare the effect of treatment", given that there is only one treatment & everyone got it? Do you want to compare some later measurement to the baseline? Which? Etc. Jun 16, 2016 at 19:24
• I meant, I want to measure the difference between the scores of each participant based on the condition (treatment) I gave them. Jun 16, 2016 at 20:39
• You must describe better how the study was organized? Were these tasks all done in sequence? Did you use a fully factorial design or latin squares? Jun 16, 2016 at 22:06
• I added the details of the study. I hope that clarifies the question a bit more? Since it's only a single task with one DV, FFD and Latin Squares are not applicable. Jun 17, 2016 at 0:11
• All right, now I'm confused. I'd thought intervals were assigned between subjects, but now I see that each subject was measured 11 times on the tiredness measure. So what's the treatment? Jun 17, 2016 at 0:13