Hi Darren,
> I am midway through my first and second level analyses now and am
> wondering how long I should expect FSL to take to finish my third level
> analysis.
Your third-level analysis looks right - yes. It's impossible to say how
long it will take, depends on your computer and details on the data (and
indeed on how much activation there is) but probably 2-6 hours... and yes
it is probably worth buying the extra RAM.
The soon-to-be-released FSL-3.1 contains nicer logging of the FLAME
processing - you get to see how far through it has got at any point.
Thanks, Steve.
>
> For each subject, I have three scans with 12 contrasts being created.
> Each of these scans take about 30 minutes to run on my Powerbook G4
> 867Mhz with 512 Mb RAM. Each second level analysis, where I just look
> for mean activations across the three scans takes about 4 hours to
> complete.
>
> 1. How long should I anticipate the third level analysis to take? How
> do I estimate this? My third level analysis will group the 18 subjects
> into three different groups of six subjects each, look at each groups'
> mean activation, and test whether the differences among groups are
> statistically significant (using the F test, right?).
>
> 2. How much of a speed increase should I anticipate if I spend $95 to
> max out the RAM to 1 GB?
>
> Darren
>
Stephen M. Smith MA DPhil CEng MIEE
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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