Hi Doug,

Thanks for your quick response - that all makes sense now.

Best wishes, Clare

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Message: 13 Date: Fri, 10 Aug 2012 10:19:43 +0000 From: "Gibbard, Clare" c.gibbard@ucl.ac.uk Subject: [Freesurfer] QDEC results To: "freesurfer@nmr.mgh.harvard.edu" freesurfer@nmr.mgh.harvard.edu Message-ID: D2ACCCB2F2AEDD40865D0836BF8D33B6224C82C9@DB3PRD0104MB131.eurprd01.prod.exchangelabs.com

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Hello,

I went on the FS course in Amsterdam recently. I have run a QDEC analysis to see whether cortical thickness differs between my two groups. I have two questions:

1. I put in the lh_bankssts_thickness as my continuous variable. The display outputs results for whether average thickness differs between my groups. The significant clusters appear in areas which are far away from the lh_bankssts. Is this correct? Does the design somehow look at overall cortical thickness in the lh even though I have only specified the lh_bankssts?

2. I can't see the button for controlling for multiple comparisons. From the wiki I believe this is supposed to appear under a scalar heading, but I can't see it. Do I need to add something in order to do this?

Thank you very much.

Best wishes, Clare

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Message: 21 Date: Fri, 10 Aug 2012 11:03:52 -0400 From: Douglas N Greve greve@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] QDEC results To: freesurfer@nmr.mgh.harvard.edu Message-ID: 502522D8.2080307@nmr.mgh.harvard.edu Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi Clare,

On 08/10/2012 06:19 AM, Gibbard, Clare wrote:

Hello,

I went on the FS course in Amsterdam recently. I have run a QDEC analysis to see whether cortical thickness differs between my two groups. I have two questions:

1. I put in the lh_bankssts_thickness as my continuous variable. The

display outputs results for whether average thickness differs between my groups. The significant clusters appear in areas which are far away from the lh_bankssts. Is this correct? Does the design somehow look at overall cortical thickness in the lh even though I have only specified the lh_bankssts?

I think it is correct. You are not confining the analysis to bankssts. You are basically using bankssts as a nuisance variable.

2. I can't see the button for controlling for multiple comparisons.

From the wiki I believe this is supposed to appear under a scalar heading, but I can't see it. Do I need to add something in order to do this?

You should not need anything else. Are you on the "Display" tab? It should be under the "Clusters" area.

doug