Chapter 25 SAS Code for the Repeated Measures

/* Compound Structure */ 
proc mixed;
    class program subj time;
    model strength = program time program * time;
    random subj(program) ;
run;

/* alternative code for compound structure */
proc mixed;
    class program subj time;
    model strength program time program * time;
    repeated time / subject = subj type = cs;   /* cs */
run; 
 
/* AR(1)  */
proc mixed;
    class program subj time;
    model strength program time program * time;
    repeated time / subject = subj type = ar(1);  
run; 

/* General Positive Definite Structure */
proc mixed;
    class program subj time;
    model strength program time program * time;
    repeated time / subject = subj type = un;
run; 

AIC and BIC for repeated measures in SAS:

• \(AIC = -2\ell(\hat\theta) + 2k\)
• \(BIC = -2\ell(\hat\theta) + k\ln(n)\)
• k = number of variance parameters
• n = total number of independent subjects