Hi FreeSurfer Experts,
With age as a continuous variable, qdec can test the linear effect of age. To test the quadratic effect of age, do I just create a curvilinear term like age*age and add into the existing equation?
For example:
original equation: Y = intercept + age + Factor + age*Factor
new equation: Y = intercept + age + Factor + age*Factor + age*age + age*age*Factor
Best,
Daniel
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Daniel (Yung-Jui) Yang, Ph.D.
Postdoctoral Researcher
Yale Child Study Center
New Haven, CT
Tel: (203) 737-5454
E-mail: yung-jui.yang(a)yale.edu