Thanks a lot. This scrip seemly describes F-test or T-test. In my study, I want to analyze the correlationship between patient's cortical thickness and pain scale (from 0 to 6). After I create data table. Qdec automatically put pain scale into continuous variable category. Actually, pain scale is ordinal variable, not continuous variable. Different correlation model should be used. How should I do it by qdec? I very appreciate your help. Hong Xie
________________________________ From: Douglas N Greve [mailto:gr...@nmr.mgh.harvard.edu] Sent: Mon 1/12/2009 3:11 PM To: Xie, Hong Cc: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] Qdec correlation analyses Not with QDEC, but you can write your own FSGD, See https://surfer.nmr.mgh.harvard.edu/fswiki/FsgdExamples Xie, Hong wrote: > Hello, > Thank you for answering me. I searched mailing list and read this > answer email: > /I see that group.levels has four levels. Unfortunately, right now > qdec only supports two levels for a discrete factor. One the features > in the works is to increase this./ > /Nick Schmansky > Wed, 27 Feb 2008 11:08:10 -0800/ > Is this question still here? I have a five levels discrete factor. Can > I run correlation statistic by Qdec? > Thanks again > Hong Xie > > ------------------------------------------------------------------------ > *From:* Douglas N Greve [mailto:gr...@nmr.mgh.harvard.edu] > *Sent:* Thu 1/8/2009 4:40 PM > *To:* Xie, Hong > *Cc:* freesurfer@nmr.mgh.harvard.edu > *Subject:* Re: [Freesurfer] Qdec correlation analyses > > > It has to be interpreted as a continuous variable. The test is done > using a t-test inside the glm. This reduces to a Pearson if there is > only one variable and no intercept (which it is not). > > doug > > Xie, Hong wrote: > > > > Hello, freesurfer group, > > > > > > > > I have run qdec for comparing thickness between two groups. When qdec > > does a correlation analyses for thickness versus a second variable: 1) > > Does the second variable have to be a continuous interval variable or > > 2) can the second variable be an ordinal variable with more than 2 > > levels? In the case of the correlation between two continuous > > variable, is the test a Pearson correlation? If 2) is possible, is the > > correlation a Spearman correlation? > > > > Thank for your help, > > > > > > > > Hong Xie > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Freesurfer mailing list > > Freesurfer@nmr.mgh.harvard.edu > > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >
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