I have to test the difference between two samples which were selected via stratified randomization. The problem is that the samples are not independent due to randomization was stratified.
How should I conduct the test?
There are 80 patients. They were strafified by weight into four groups, each containing 20 observations. There are 4 treatments A,B,C,D. 5 patients from each group were randomly assigned to each of the four treatments.
The question is how to compare these treatments?
Weight is known to be the most important factor influencing the desease. The researcher tries to "adjust for weight", i.e., to provide "balance" of weights among the treatments.
The problem in comparing treatments for each weight separately is that we will then have only 5 observations per group.