In a drug test experiment, we measure the effects of different concentrations of a drug on multiple subjects. The main variable we measure is the distance traveled by the subjects (one record per minute). Some subjects are not treated as they act as a control.
What we would like to know is to conclude if the drug is effective in any way. The problem here is to know when time is a factor in a problem like this.
The drug is applied before the experiment, so time is not exposure time to the drug. But could be some behavior patterns over time, like subjects moving faster at the beginning and become slower at the end because of fatigue. Control should have this behavior but subjects treated maybe not.
Also, we have 4 phases that change over time in groups of 10 minutes that also alter these behavior patterns (light changes) and cause reactions in the speed of the subjects, especially just after the change.
So in this problem time has a very important role but it is never the cause of the effect.
Is this a Repeated Measures ANOVA or time is a factor?