Bioequivalence and Bioavailability Forum

Dear John,

❝ Is there a way to extract the intersubject CV from Proc Mixed for a 3-way partial replicate study (Based on the ABE part of the FDA RSABE Proc Mixed code)?

From the FA0(2) parametrization there are complicated formulas conecting the covariance parameters with the intersubject CV's.
A simpler way would be to request the output of the G-Matrix via
   RANDOM treat/TYPE=FA0(2) SUB=subject G;
If you used the FDA code the G-Matrix is already requested

This matrix can be interpreted as
(   s2bT     rho*sbT*sbR )
( rho*sbT*sbR   s2bR     )
where the diagonal elements (inter-subject variances) can be converted to the CV's via
CVbT=sqrt(exp(s2bT)-1)
CVbR=sqrt(exp(s2bR)-1)

Cave on the order in the G-Matrix. It depends on your coding for treatment.

BTW: This way is not restricted to the partial replicate design but is general. But in case of it the trust in the numbers is restricted (at least by me ).