Dear colleagues, I have recognized that the diagonal elements of the correlation matrix of estimates are not equal to 1 as one would expect. I have attached the output of the theophylline test data set, obtained with NM730. It seems that each diagonal element in the correlation matrix is just the square root of the corresponding value in the covariance matrix. The off-diagonal elements, however, are correct. When looking at older NONMEM versions, this occurred also in NM720 but not in NM712. Of course, nobody would really pay attention to the diagonal elements of a correlation matrix, but it looks odd and should be corrected in future versions.
Best regards Harald Ihmsen Dr. Harald Ihmsen Anästhesiologische Klinik Universitätsklinikum Erlangen Krankenhausstr. 12 91054 Erlangen Tel: ++49 (9131) 8539157 Fax: ++49 (9131) 8539161 e-mail: [email protected] ************************************************************************************************************************ ******************** ******************** ******************** FIRST ORDER ******************** ******************** CORRELATION MATRIX OF ESTIMATE ******************** ******************** ******************** ************************************************************************************************************************ TH 1 TH 2 TH 3 OM11 OM12 OM13 OM22 OM23 OM33 SG11 TH 1 + 7.08E-01 TH 2 + 2.27E-01 7.26E-03 TH 3 + 1.42E-02 9.47E-01 4.53E-03 OM11 + 9.69E-01 1.78E-01 -1.76E-02 4.83E+00 OM12 + 4.36E-01 7.12E-01 5.95E-01 3.19E-01 1.40E-02 OM13 + 9.01E-03 4.60E-01 4.78E-01 -1.38E-01 7.57E-01 4.75E-01 OM22 + 8.48E-02 4.72E-01 3.86E-01 -1.22E-02 8.22E-01 7.05E-01 1.22E-04 OM23 + 7.55E-03 -5.66E-02 -4.93E-02 -1.30E-01 4.39E-01 6.65E-01 6.88E-01 3.73E-03 OM33 + 4.10E-02 -2.42E-01 -1.72E-01 -8.42E-02 1.96E-01 5.11E-01 3.29E-01 8.95E-01 2.12E-01 SG11 + -1.71E-01 2.61E-01 1.27E-01 -2.68E-01 4.54E-01 3.51E-01 5.85E-01 2.41E-01 -6.81E-02 1.05E-01
