Here is the problem I have (the figure below tries to depict the problem):
- There are two groups of patients - the BURN_GRP and the TVC_GRP, and all the patients are different (i.e. no patients in the BURN_GRP appear in the TVC_GRP and vice versa).
- The number of patients in each group is different, 125 vs. 219 (but I can randomly discard patients from the TVC_GRP in order to have the same number of patients in each group).
- Each patient has four measures of their SA_VAL taken over time (6 hours apart).
- I would like to test the hypothesis that the average SA_VAL of the patients in the BURN_GRP is statistically significantly different than the average SA_VAL of the patients in the TVC_GRP.
If there were no repeated measures I would perform a standard (non-paired) t-test. However, now that there are four (non-independent) measures for each patient I am unsure about how to proceed. I think it might be a repeated measure ANOVA. Is it? If so, how would I go about modeling it in R?