Dear Sophie,
You have two within-subjects factors with two levels each here so I
would recommend to compute a contrast image for each main effect and
interaction for each subject and enter these in a one-sample t-test at
the second level, ie at first level, compute:
main effect of drug: [1 1 -1 -1]
main effect of cardiac: [1 -1 1 -1]
drug x cardiac interaction: [1 -1 -1 1]
Best regards,
Guillaume.
On 03/05/18 09:31, Sophie Betka wrote:
> Dear Spm users,
>
>
>
> Could you let me know if what I did is correct? Thanks a lot
>
>
>
> So I am using a 2*2 flexible design (within-subjects design with
> Subjects, Drug:2 Levels ; CardiacTiming:2 Levels).
>
>
>
>
>
> 1) I attached a screen shot of my batch. The variance of Drug and
> Cardiac should be unequal right?
>
> I am interested in main effect of Drug, main effect of
> Cardiac and the interaction.
>
>
>
> 2) I attached a screen shot of the design matrix.
>
> Following the Glascher’s paper, I created contrasts.
>
>
>
> Could confirm/correct my contrasts:
>
>
>
>
>
>
>
> Drug1
>
>
>
> Durg2
>
>
>
> Card1
>
>
>
> Card2
>
>
>
> D1C1
>
>
>
> D1C2
>
>
>
> D2C1
>
>
>
> D2C2
>
> Main effect of Drug
>
>
>
> 1
>
>
>
> -1
>
>
>
> 0
>
>
>
> 0
>
>
>
> 0.5
>
>
>
> 0.5
>
>
>
> -0.5
>
>
>
> -0.5
>
> Main effect of Cardiac
>
>
>
> 0
>
>
>
> 0
>
>
>
> 1
>
>
>
> -1
>
>
>
> 0.5
>
>
>
> -0.5
>
>
>
> 0.5
>
>
>
> -0.5
>
> Interaction Drug*Cardiac
>
>
>
> 0
>
>
>
> 0
>
>
>
> 0
>
>
>
> 0
>
>
>
> 0.5
>
>
>
> -0.5
>
>
>
> -0.5
>
>
>
> 0.5
>
> Test single repressor Drug1
>
>
>
> 1
>
>
>
> 0
>
>
>
> 0.5
>
>
>
> 0.5
>
>
>
> 0.5
>
>
>
> 0.5
>
>
>
> 0
>
>
>
> 0
>
> Test single repressor D2C2
>
>
>
> 0
>
>
>
> 1
>
>
>
> 0
>
>
>
> 1
>
>
>
> 0
>
>
>
> 0
>
>
>
> 0
>
>
>
> 1
>
>
>
> The main effect of cardiac gives me a massive cluster; this a bit odd
> (enclosed).
>
>
>
>
>
> Thank you for your help,
>
> S.
>
>
>
>
>
>
>
>
>
> *Sophie BETKA*
> *Ph.D Student*
> *Neuropsychologist*
>
> *Brighton and Sussex Medical School*
>
> Neurosciences Department - CritchleyLab
>
> /Trafford Centre, 202 (Brighton, UK)/
>
> University of Sussex, Falmer, BN1 9RR
> +44 (0)1273 873132
>
> *SCALab - Cognitive and Affective Sciences Laboratory*
> /DEEP Team - Emotional Dynamics and Pathology (Lille, FR)/
> Faculté de Medecine, Pôle Recherche
> 1, Place de Verdun, 59045 Lille cedex
>
> +33 (0)3.20.62.68.13
>
> _Twitter @SophieBetka <https://twitter.com/SophieBetka>___
>
> _ResearchGate <https://www.researchgate.net/profile/Sophie_Betka>___
>
> _Linkedin <https://www.linkedin.com/in/sophie-betka-54b149155/>___
>
>
>
>
>
>
> ___________________________________________________________
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--
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