yes, qdec can only have 2 factors with 2 levels. both qdec and mri_glmfit are linear methods (in fact, qdec just calls mri_glmfit).

On 7/3/2019 9:39 AM, Marie Hill wrote:

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Dear Sir/Madam,

Could I post the following message to the mailing list:

I am running a regression testing for significant difference in cortical volume, thickness etc with 3 factors: diagnosis, genotype and gender, with age as a nuisance factor.

I am using qdec but receiving Error: factor 2 must have 2 levels.

Is it true that Qdec only supports factors with 2 levels? There is a page for qdec levels stating to create a file diagnosis.levels and state the three levels. I did this however the same error occurs.

I was going to use glm_fit instead but I think my study isn't a linear regression so isn't suitable (as I am not interested in the change with age, just between groups).

Kind regards,

Marie
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