From: bvatul <bvatul@ufl.edu>
Subject: Error message in $COV step
Date: Mon, 09 Jul 2001 17:35:37 -0400
Hello All
Could somebody please clarify this?
I was analysing a data set with $COV estimation step. I was encountering
this error and the program took several hours to converge in the final
steps. The code is written below:
$PK
TVCL1=THETA(1)
TVV1=THETA(2)
TVK12=THETA(3)
TVK21=THETA(4)
CL1=TVCL1*EXP(ETA(1))
V1=TVV1*EXP(ETA(2))
K12=TVK12*EXP(ETA(3))
K21=TVK21*EXP(ETA(4))
$ERROR
Y=F*(1+ERR(1))+ERR(2)
$EST METHOD=1 INTERACTION MAXEVAL=9999 PRINT=5 NOABORT POSTHOC
This is the message which I see in the output. I was wondering was this
means and what could the problem be?
0MINIMIZATION SUCCESSFUL
NO. OF FUNCTION EVALUATIONS USED: 673
NO. OF SIG. DIGITS IN FINAL EST.: 3.0
ETABAR IS THE ARITHMETIC MEAN OF THE ETA-ESTIMATES,
AND THE P-VALUE IS GIVEN FOR THE NULL HYPOTHESIS THAT THE TRUE MEAN IS
0.
ETABAR: -.44E-02 -.57E-02 -.14E-02 .14E-02
P VAL.: .78E+00 .74E+00 .70E+00 .81E+00
0R MATRIX ALGORITHMICALLY NON-POSITIVE-SEMIDEFINITE
BUT NONSINGULAR
0COVARIANCE STEP ABORTED
1
Thanks in advance
Atul