Hi Tudor
I'll leave ths stats question to Martin or Jorge, but I'm not sure why the wiki would say out longitudinal stream is not optimal. It is certainly as optimal as we have had the resources to make it, although there are a long list of things we would still like to do.
cheers Bruce
On Thu, 8 May 2014, Tudor Popescu wrote:
Sorry for the repeat, wasn't sure whether this was received the first time. Tudor
On 6 May 2014 19:55, Tudor Popescu tudor3@gmail.com wrote: Dear FS list,
I have structural data from a learning study (pre&post-training scans, with 3 groups). Although the training was only one week, I'm guessing from an analysis point of view, this still qualifies as longitudinal. I want to check for
- the main within-subjects effect of time point (pre&post)
- the main between-subjects effect of group (treatment A, treatment B, control),
- the time x group interaction
I intend to look at thickness, surface area, volume, and lGI.
I read on the wiki that FS is currently not optimal for longitudinal analyses. I intend my FreeSurfer analysis to supplement a VBM analysis done in FSL. In case it is in fact a good idea to do this, my questions (not covered in the 'longitudinal' wiki page) are:
- Can QDEC be used for such an analysis, and if so, what would be
different as compared to a cross-sectional (no temporal/within factor) study?
Also, is the pre-processing stage any different?
In FSL, for longitudinal designs you do stats on images obtained as
the difference between consecutive time points. Does this have to be done in FreeSurfer as well, and if so, is it done at the recon-all level or only at the stats (QDEC) level?
Thanks!
Tudor