Subject: Categorical covariates with more than two levels on qdec
Categorical covariates with more than two levels on qdec
Dear Freesurfer experts,
I am doing an analysis on a large data set gathered from eight different imaging centres. In my analysis I would like to covary for the imaging site but qdec only allows me to covary for categorical variables if they have two levels (and I have eight). I am also using age (continuous) and gender (categorical, two levels) as covariates.
Is there a way of using the imaging site as a covariate using qdec? Do you have any suggestions on how I should proceed? Is treating imaging site as a continuous variable acceptable?
Best wishes,
Hanna
You cannot use qdec for this. You must use the "command line stream". There is a tutorial for this as well as a presentation on our wiki. Basically, you will need to create your FSGD file, run mris_preproc, mri_surf2surf to smooth, mri_glmfit, and mri_glmfit-sim
doug
On 07/09/2014 03:43 AM, Isotalus, Hanna wrote:
Subject: Categorical covariates with more than two levels on qdec
Categorical covariates with more than two levels on qdec
Dear Freesurfer experts,
I am doing an analysis on a large data set gathered from eight different imaging centres. In my analysis I would like to covary for the imaging site but qdec only allows me to covary for categorical variables if they have two levels (and I have eight). I am also using age (continuous) and gender (categorical, two levels) as covariates.
Is there a way of using the imaging site as a covariate using qdec? Do you have any suggestions on how I should proceed? Is treating imaging site as a continuous variable acceptable?
Best wishes,
Hanna
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Douglas N Greve -
Isotalus, Hanna