Hello,
I have three groups: healthy controls, pre-surgery, and post-surgery. The pre and post-surgery are the same patients who participated in the study before and 10 months after their operations. The healthy controls were matched to the patient group based on anthropometrics. My issue is what test to select considering 1 of the 3 testable groups are independent while the other 2 are dependent. I have considered the following options:
1) Repeated measures ANOVA: Even though the healthy controls were matched, I still am not confident that they are matched well enough to be considered the 'same' as the injured groups.
2) One-way ANOVA with t-tests as post-hocs. Is it appropriate to use independent t-tests fro healthy vs pre op and healthy vs post-op but a paired samples t-test for pre vs post-op? Would I have to correct my alpha from 0.05 to (.05/3) 0.0167 because of the three tests even though I'm doing 2 independent and 1 paired?
3) Treating each comparison as a separate research question: Q1) Independent t-test between healthy and pre-op. Q2) Paired samples t-test between pre and post-op. Q3) Independent t-tests between post-op and healthy. I still have the issue of what to correct my alpha to because 0.0167 appears to be much too conservative when visualizing the data in the figures.
Any advice on this matter will be greatly appreciated!
Thanks.
I have three groups: healthy controls, pre-surgery, and post-surgery. The pre and post-surgery are the same patients who participated in the study before and 10 months after their operations. The healthy controls were matched to the patient group based on anthropometrics. My issue is what test to select considering 1 of the 3 testable groups are independent while the other 2 are dependent. I have considered the following options:
1) Repeated measures ANOVA: Even though the healthy controls were matched, I still am not confident that they are matched well enough to be considered the 'same' as the injured groups.
2) One-way ANOVA with t-tests as post-hocs. Is it appropriate to use independent t-tests fro healthy vs pre op and healthy vs post-op but a paired samples t-test for pre vs post-op? Would I have to correct my alpha from 0.05 to (.05/3) 0.0167 because of the three tests even though I'm doing 2 independent and 1 paired?
3) Treating each comparison as a separate research question: Q1) Independent t-test between healthy and pre-op. Q2) Paired samples t-test between pre and post-op. Q3) Independent t-tests between post-op and healthy. I still have the issue of what to correct my alpha to because 0.0167 appears to be much too conservative when visualizing the data in the figures.
Any advice on this matter will be greatly appreciated!
Thanks.