How does one compare means between two groups that contain repeated measures. For instance:
Group 1 = has mutation A
Group 2 = has mutation B
Dependent variable = blood pressure (continuous variable)
Group 1 has 140 data points and 52 participants. Group B has 120 data points and 30 participants. Some participants have five measurements of blood pressure, others have four, and yet others can have only one. This is not a "repeated measures" analysis because we are not studying the effect of time or diet or anything like this on blood pressure. Some participants simply have more measurements than others.
Approach 1. Take one random measurement per participant.
Approach 2. Take the first measurement from each participant.
Approach 3. Take the average of all measurements from each participant.
Approach 4. Take all the data points and run a t-test ignoring the problem.
Approach 5. ?Something better? Please say that this is possible.
For bonus marks, could someone tell me how to implement this in SPSS?
Thanks for your time.