From: "Olofsen, E. (ANST)"Subject: [NMusers] correlation function for the epsilons Date:Wed, 14 May 2003 22:35:57 +0200 Dear group, I wanted to specify a correlation function for the epsilons as discussed in: http://www.cognigencorp.com/nonmem/nm/98jul101998.html Furthermore, I wanted to test this with single-subject data. At the end of the above link it is noted that the single-subject data should be entered as population data, but with OMEGA constrained to zero. However, when the data file and $INPUT contain the ID item, the covariance step does not give correct results (the estimation step does). If I remove `ID', NONMEM gives a warning about the SIGMA matrix, it treats every observation as coming from a different individual, and I wonder if the above technique will work. Does anyone know how I should proceed? Thanks in advance, Erik Olofsen Leiden University Medical Center PS: An example (t.d contains e.g. [1 0; 1 1; 1 2; 1 3]): $PROBLEM indeed $DATA t.d $INPUT ID DV $PRED A = THETA(1)+ETA(1) Y = A+ERR(1) $THETA 1 $OMEGA 0 FIX $SIGMA 0.1 $ESTIMATION MAX=9999 SIG=4 PRINT=1 $COVR _______________________________________________________