I have a question about what's the ideal test to run for my study design. I would appreciate any advice!
• One within-subjects factor: time (5 levels)
• 2 between-subjects factors: group (2 levels) and treatment (2 levels)
• And one dependent variable which is the levels of a biomarker in the blood.
I would like to see if the change in the biomarker levels significantly differ between the groups in response to the treatment over time.
Is it okay if I do a three-way(2x2x5) mixed ANOVA on this? A colleague told me that it is completely wrong to use an ANOVA and that I should do a linear mixed model instead.
Any advice or opinions about this would be helpful!
Thanks in advance!
Edit: The same individuals were measured over 5 timepoints. So, it's a repeated measures design. Each group (2 groups in total) of individuals were divided into 2 sub-groups. First sub-group received treatment A, the second group received treatment B. Each sub-group is around 20 individuals. So, 40 individuals per group, and 80 individuals in the whole experiment. The timepoints are evenly spaced (every week).