Hi Alex
I would think that longitudinal analysis is still the way to go as we try to improve both reliability and sensitivity using the fact that we have multiple scans/subject.
cheers Bruce On Tue, 3 Jun 2014, Alexandru Hanganu wrote:
Hello Everyone,
could someone please give us an advice about which method you consider is the best for our study ?
we have two groups with MRI at Time 1. Each group received medication. After this we performed another MRI at Time 2 after 2 weeks.
The best method for this study is a longitudinal one or a cross-sectional GLM ?
We consider that the distance between the time points is too small, and the longitudinal method is not the best choice. Hence, this study should be treated as a cross-sectional one. In this case we think about performing a simple GLM with the contrasts: 0.5 0.5 0.5 0.5 or 1 -1 -1 1
for the groups:
- grp 1 time 1
- grp 1 time 2
- grp 2 time 1
- grp 2 time 2
we are searching to see whether medication had any impact on the cortical morphology in each group and between the groups.
Thank you ! Best regards, Alex.