Yes, that looks right (assuming that cortisol is your first variable)

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On 11/7/2023 3:49 PM, Laura Willers de Souza wrote:

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Hello FreeSurfer Developers,

Following the FSGD examples on the website, I built the following test:

                Question: Is there an association between cortisol and
                cortical 

                thickness regressing out the effect of sex, age,
                APOE4_carrier (1=1 or 

                2 alleles, 0=no alleles), abeta, ptau, diagnosis (CU and
                CI)? 

                Regressors: 2 factors (sex, diagnosis) with 2 levels
                each, 5 

                covariates (age, APOE4_carrier (1=1 or 2 alleles, 0=no
                alleles), 

                abeta, ptau, cortisol) >> 24 regressors

Contrast: 0 0 0 0 0.5 -0.5 0.5 -0.5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
FSGD:
GroupDescriptorFile 1
Title CSF_semgrupos
Class MaleCU
Class MaleCI
Class FemaleCU
Class FemaleCI
Variables Cortisol Age ABETA ptau APOE4_carrier
Input 098_S_4003_I224603 MaleCI 11 81.3 741.5 22.83 1

Does this feel right to you?

                I am having difficulty understanding how to construct
                the contrast to 

                answer the following question "Is the interaction
                between group 

                (CU/CI) and cortisol significant regressing out the
                effect of sex, 

                age, APOE_carrier, abeta and ptau?" It seems like the
                contrast would 

                be the same as before.. Can you guys help me with this?

Thanks in advance!

*Laura Willers de Souza *

PhD Student in Pharmacology and Therapeutics

Zimmer Lab - Federal University of Rio Grande do Sul

- Porto Alegre/RS - Brazil
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