Hi, I am quite new to R and trying to analyze the following data. I have 28 controls and 25 patients. I measured X values of 4 different locations (A,B,C,D) in the brain image of each subject. And X ranges from 0 to 1. I think "control or patient" is a between subject factor and location is a within subject factor. So,
controls: 28 patients: 25 (unbalanced data set) respone measure: X values (ranging 0 to 1) fixed factor: control vs. patient (between subject factor) random factor: location (level: A,B,C,D ;no order) (within subject factor) random factor: subjectID 1-53 My data looks like this; CorP X location subjectID control 0.708 A 1 control 0.648 A 2 patient 0.638 C 3 control 0.547 D 4 patient 0.632 B 5 control 0.723 C 6 ........... I want to know (a) if there is a significant difference between controls and patients in X values. (b) where (A,B,C,D?) the difference is between controls and patients in X values. (There may be an interaction) I constructed linear mixed model with lme as followings; (1) model1 <- lme(X ~ CorP*location, random= ~ 1| subjectID, mydata) (2) model2 <- lme(X ~ CorP*location, random= ~ location| subjectID, mydata) I am not familiar with lme syntax. I'm just wondering which formula [(1) or (2)] is appropriate for my model to know answers of (a) and (b) questions. Or may be both of the formulas are wrong. I would appreciate it very much if somebody could help me. Sincerely, Kohkichi Hosoda ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
