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IMP method: covariance matrix was absent from output file even though estimation succeeded.

From: Bach, Thanh H Y <thanh-bach>
Date: Thu, 8 Oct 2020 20:24:30 +0000

Hi all,

I am running a model using IMP method. Model optimization was successful but no covarance matrix was output unless I specify UNCONDITIONAL in the $COV block. Any idea why?

When I read the user guide, it said that UNCONDITIONAL is needed if we want the covariance step to be implemented even when model minimization fails. It did not mention anything about successful minimization but no covariance output. I also checked NONMEM output file for my model and there was not error message either, so I am not sure the missing covariance matrix was due to $COV failure or any other reason.

Following is a snapshot of my model output

 iteration 90 OBJ= 6617.1481876524931 eff.= 93. Smpl.= 300. Fit.= 0.88856

 #TERM:
 OPTIMIZATION WAS COMPLETED


 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: 4.9637E-03 9.3967E-03 3.7603E-05 -1.9003E-04
 SE: 4.9923E-02 9.6445E-02 2.7522E-02 2.6685E-03
 N: 56 56 56 56

 P VAL.: 9.2080E-01 9.2238E-01 9.9891E-01 9.4323E-01

 ETASHRINKSD(%) 2.7783E+00 1.7267E+01 5.3092E+00 6.9977E+01
 ETASHRINKVR(%) 5.4794E+00 3.1553E+01 1.0337E+01 9.0986E+01
 EBVSHRINKSD(%) 2.7482E+00 1.7184E+01 5.6691E+00 7.0131E+01
 EBVSHRINKVR(%) 5.4209E+00 3.1415E+01 1.1017E+01 9.1078E+01
 EPSSHRINKSD(%) 1.2374E+01 1.2374E+01
 EPSSHRINKVR(%) 2.3217E+01 2.3217E+01


 TOTAL DATA POINTS NORMALLY DISTRIBUTED (N): 578
 N*LOG(2PI) CONSTANT TO OBJECTIVE FUNCTION: 1062.2929443846017
 OBJECTIVE FUNCTION VALUE WITHOUT CONSTANT: 6617.1481876524931
 OBJECTIVE FUNCTION VALUE WITH CONSTANT: 7679.4411320370946
 REPORTED OBJECTIVE FUNCTION DOES NOT CONTAIN CONSTANT

 TOTAL EFFECTIVE ETAS (NIND*NETA): 224

 #TERE:
 Elapsed estimation time in seconds: 28.83

 Number of Negative Eigenvalues in Matrix= 1
 Most negative value= -7.5944835791791885
 Most positive value= 29811.764851258835
 Forcing positive definiteness
 Root mean square deviation of matrix from original= 6.6243382481674822E-006

 Elapsed covariance time in seconds: 0.28

‚ÄčThank you in advance for your feedback
Received on Thu Oct 08 2020 - 16:24:30 EDT

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