Hi - I would think that you should be able to setup a second-level FE
within-subject model that takes in all first-level COPEs (possibly
using the "inputs are copes" input type option, rather than the
"inputs are FEAT directories" options). You then just need one EV per
condition (eg one for face and one for object) in this second-level
model.
Cheers.
On 18 May 2009, at 21:01, Jessica Kirkland wrote:
> Hi,
>
> I am currently analyzing data for 70 subjects, 3 runs each. I would
> like to set up a 3-level analysis like this: level 1 = run, level 2
> = subject, level 3 = group. My problem is that each subject has 2
> runs containing face stimuli, and one run containing object stimuli--
> so I do not want to average all 3 at the subject level.
>
> I am unsure of how to make my 2nd level fixed-effects analysis take
> this into account (e.g., I could do a 2nd level combining across the
> face runs, but what about the object run?). Is there a way to do
> this at the second level without averaging across all 3 runs? I
> tried to get around the issue by entering all 3 runs' feat
> directories, and then setting up 2 contrasts, one combining the 2
> face runs and 1 representing the object run, but Feat crashed
> because the runs have different #s of copes.
>
> Alternatively, could I run two separate 2nd-level fixed effects
> analyses--one for face runs and one for the object run? If I am
> understanding correctly, it would not be appropriate to input all
> runs separately into a higher-level ME Flame analysis, or to input
> some 1st (object runs) and some 2nd (face runs) level data at the
> 3rd level. In any case it seems that I may run into the different #
> of copes issue at the 3rd level as well...
>
> Any suggestions on how to proceed would be greatly appreciated.
>
> thank you,
>
> Jessica
---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
---------------------------------------------------------------------------
|