External Email - Use Caution Dear Douglas,
Thank you so much for your answer! Sorry, but I don't think I explained myself correctly in the previous email. I want to analyze the difference in cortical thickness between two groups (CU and CI), adjusting for a covariate (cortisol CSF) and the interaction between them. So my model would be: cortical thickness ~ diagnosis + CSF cortisol + diagnosis*CSF cortisol Using the GLM DODS, the contrasts, according to the wiki example (https://secure-web.cisco.com/1PUyQNFnXt6UhBGwXfB_vPfCTd6uW7Jf3dH3GiO0aIPFHhasIc93wuEMuO9UVzFWp8t9mtGwYhsl8vZ6NEabuPbyosKI_7KeTp-pWhlr6H4MJo3LW_FkRcnE3uQmRbYiDA8Sl16uPVL5hVt8AoD9pV5ANIRjvx80bYmcdaInwLSQstTseDNZKELz07yVpWViSweH1789PgrOyDtgpSO_lM1ydJrhnMxb8WZbp5OXzSYAD9tMwKccSM5avOhEvgD0Q6UndXNOluK0FnoXdrVCQ_jTdkr2CnMJRZwyGSMeKe4ad-h94CMfC0JkYfcXLQHS9IM40lyJnZQYJdpjj2C5bxA/https%3A%2F%2Fsurfer.nmr.mgh.harvard.edu%2Ffswiki%2FFsgdf2G1V), would be: * To verify if only the diagnosis regression coefficient is significant (diagnosis changes cortical thickness regardless of cortisol): * 1 -1 0 0 * * To verify if the regression coefficient of the interaction between diagnosis and cortisol is significant (the two change cortical thickness dependently): * 0 0 1 -1 * * To verify if only the cortisol regression coefficient is significant (cortisol changes cortical thickness regardless of diagnosis): * 0 0 0.5 0.5 Are these contrasts corret to represent the model we designed? Thank you so much again! Best regards, Laura Willers de Souza Master Student in Biochemistry Zimmer Lab - Federal University of Rio Grande do Sul - Porto Alegre/RS - Brazil
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