Here iis an explanation of why the error messages were being produced by PREDPP.
At my request, Achim send me the $MODEL statement from the control stream. $MODEL NCOMP = 4 COMP=(G0) COMP=(G1) COMP=(G2) COMP=(G3) Compartment 1 is the default compartment for doses and observations, because no compartment has the name CENTRAL or the attribute DEFOBS. PREDPP always needs to compute a scaled compartment amount as the argument F for the ERROR routine. When compartment 1 is off and PREDPP needs to get the prediction from compartment 1 , the error messages are produced. 0DATA REC 4: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF 0DATA REC 5: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF 0DATA REC 6: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF Here's a work around, as Ahmed Suleiman suggested: $MODEL NCOMP = 5 COMP=(G0) COMP=(G1) COMP=(G2) COMP=(G3) COMP=(DUMMY,DEFOBS) Also add to the end of the $DES block: DADT(5)=0 Now compartment 5 is default for observations and there are no error messages. Martin Bergstrand made a number of suggestions. The one that is directly related to these error messages is to use "a EVID = 4 dose to reset all compartments rather than resetting them 1 by 1." EVID=4 is "reset and dose". All compartments are set to 0, and then the dose is applied to compartment 1. The data would look like this. No changes to $MODEL or $DES are needed, because compartment 1 is never turned off. C ID TIME DOSE DV EVID CMT AMT MDV 1 0 0 0 1 1 1 1 1 1 50 1 0 1 0 0 1 1 50 0 4 1 1 1 1 1 50 0 2 2 0 1 1 1 50 0 2 3 0 1 1 1 50 0 2 4 0 1 Martin made other valuable suggestions but I am just trying to explain the error messages.
