I have patient mental and physical health scores and looking for differences pre and post injury. The injuries are categorical by anatomic site and severity. I was told to run a GEE with Walds test and everything came back significant, which doesn't make sense to me. Why should an ankle injury be as significant as a spinal injury? Since this data is collected every few years, I doubt a twisted ankle would leave significant decreased mental health scores after a few years. Something is not right.
Doing some research, I'm finding a ANCOVA or repeated measures ANOVA to be appropriate. However, when I run those tests I'm not seeing which classes are significant, just overall significance of the injury site / severity.
Can someone guide me to which is the appropriate test and if I'm using SAS, how to see significance by class?
Information about the data: injury group = 21,400 no injury group = 5900 dependent variables are continuous Quality of Life score(can be pre and post or can calculate change in pre/post, either way continuous) predictor variables are categorical (can be 2 variables, anatomic site + severity, or combined as 1 variable), also have some covariates anatomic site is 8 levels (1-8) severity is 5 levels (A-E) so they can be combined as 1A, 1B, ... 8E
Most important information is which anatomic site / severity class level are significant and which are not.
I ran Cohens d and got little to moderate effect size. I got higher effect sizes by stratifying by anatomic site + severity (1A, 1B, ... 8E) but still highest is 0.4.