Assume that I have a set of subjects undergoing a treatment. Every day in the morning each subject takes a (variable) dose of medication. Every day in the evening we measure the parameter of interest.
The treatment lasts 4 days, i.e. for each subject we have 4 doses injected (one each morning) and 4 measurement of the variable of interest (measured each night)
It is a repeated measures problem, with the particularity of having the predictor changing every day (the dose injected is not the same every day).
Which test should I use to determine whether the treatment (dose injected in the morning) affect the output (variable measured at night)?