Hello,

Just getting in touch regarding my design matrix for a 2x2 mixed anova with few repeat measures. I understand I can’t use exchange blocks here, and my current design matrix (attached) has columns for age group, sex, age*sex, and each subject.

When I run the contrast [1 0 0 0…] to assess main effect of age group, I get a rank deficiency error. Please let me know what I’m doing wrong! Thanks for your time.

Best,

Ed