Hi - this will be rank deficient - so I would instead follow the
examples in the FEAT manual - see for example the 'triple-t-test'
example.
Cheers.
On 6 Aug 2009, at 12:32, Martin M Monti wrote:
> Illuminated FSL masters,
>
> I am following a patient longitudinally, on a series of different
> tasks.
>
> Say the design is 1 subject performing 2 tasks each repeated 4 times.
>
> Would this set-up be correct?
>
> EV1: Overall subject mean [is this actually needed?]
> EV2: Task1 mean
> EV3: Task2 mean
> EVs4-7: Task1_T0 (reference group), Task1_T1, Task1_T2, Task1_T3
> EVs8-11: Task2_T0 (reference group), Task2_T1, Task2_T2, Task2_T3
>
> (visually..)
> Input File
> [Task1 T0] 1 1 0 0 0 0 0 0 0 0 0
> [Task1 T1] 1 1 0 0 1 0 0 0 0 0 0
> [Task1 T2] 1 1 0 0 0 1 0 0 0 0 0
> [Task1 T3] 1 1 0 0 0 0 1 0 0 0 0
> [Task2 T0] 1 0 1 0 0 0 0 0 0 0 0
> [Task2 T1] 1 0 1 0 0 0 0 0 1 0 0
> [Task2 T2] 1 0 1 0 0 0 0 0 0 1 0
> [Task2 T3] 1 0 1 0 0 0 0 0 0 0 1
>
> Contrasts & F-tests would be as follows:
>
> C1: 0 0 0 0 1 0 0 0 0 0 0 F1 (i.e. EV5)
> C2: 0 0 0 0 0 1 0 0 0 0 0 F1 (i.e. EV6 )
> C3: 0 0 0 0 0 0 1 0 0 0 0 F1 (i.e. EV7)
>
> C4: 0 0 0 0 0 0 0 0 1 0 0 F2 (i.e. EV9)
> C5: 0 0 0 0 0 0 0 0 0 1 0 F2 (i.e. EV10)
> C6: 0 0 0 0 0 0 0 0 0 0 1 F2 (i.e. EV11)
>
>
> Contrasts & Ftests interpretations:
>
> F1 is the within subject effect for Test1
> F2 is the within subject effect for Test2
> Each contrasts is essentially like a Dunnett test (i.e. comparison
> of each repetition to its reference group). However, without the
> actual multiple comparisons correction of the Dunnett test
> (considering the number of voxels tested a few multiple comparisons
> are maybe not that big of an issue?!).
>
> Does this sound about right?
>
> cheers
>
> martin
>
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
|