I'm sure a more senior person on the mailing list could give you a better answer. My impression is that 5-7 patients would be enough for a case study, i.e. "What does Network X look like in patients with Disease Y?" Such a low number of patients would probably be pushing it for a systematic analysis, especially if you don't have control subjects! But again, if the conditition you are studying has a dramatic effect on connectivity (i.e. very large effect size) then it might be enough.
On Wednesday, August 15, 2012 10:17:46 you wrote:
> Dear Benjamin,
> Thank you for this response.
> I must deal with some rare clinical cases (5 to 7 patients, for instance): is it
> possible to use MELODIC group-analysis for this very small population? or is it
> statistically irrelevant?
> Thank you.
> Selon Benjamin Kay <[log in to unmask]>:
> > Christophe,
> > That will depend entirely on your hypothesis and expected effect size. The
> > final stage of analysis with MELODIC ICA + dual regression typically involves
> > some sort of GLM (often a t-test) to compare connectivity between two or more
> > experimental groups. The standard techniques for estimating effect size (e.g.
> > Cohen's d) and power apply. Since your experimental protocol will influence
> > the standard error, and thus the effect size, of your data, the best way to
> > figure out how many subjects you need is to collect pilot data and estimate
> > your effect size and power from that. As a very rough ballpark figure, I have
> > seen ICA based publications with fewer than 20 total subjects.
> > Hope this sets you on the right track,
> > Benjamin
> > On Wednesday, August 15, 2012 09:10:07 you wrote:
> > > Dear experts,
> > >
> > > I would like to know the lower population size required to compute MELODIC
> > ICA
> > > group-analysis.
> > >
> > > Thank you.
> > > Best,
> > > Christophe
> > >