Hello Hauke, as always for these specific questions you need to provide us with the relevant portions of your control stream and of your output.
Thanks for participating, Joachim _________________________________ AstraZeneca R&D Charnwood Clin. Pharmacology and DMPK Bakewell Road Loughborough, LE11 5RH Tel: +44 1509 644035 [email protected] -------------------------------------------------------------------------- AstraZeneca UK Limited is a company incorporated in England and Wales with registered number: 03674842 and a registered office at 15 Stanhope Gate, London W1K 1LN. Confidentiality Notice: This message is private and may contain confidential, proprietary and legally privileged information. If you have received this message in error, please notify us and remove it from your system and note that you must not copy, distribute or take any action in reliance on it. Any unauthorised use or disclosure of the contents of this message is not permitted and may be unlawful. Disclaimer: Email messages may be subject to delays, interception, non-delivery and unauthorised alterations. Therefore, information expressed in this message is not given or endorsed by AstraZeneca UK Limited unless otherwise notified by an authorised representative independent of this message. No contractual relationship is created by this message by any person unless specifically indicated by agreement in writing other than email. Monitoring: AstraZeneca UK Limited may monitor email traffic data and content for the purposes of the prevention and detection of crime, ensuring the security of our computer systems and checking Compliance with our Code of Conduct and Policies. -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of Hauke Rühs Sent: 03 August 2009 15:07 To: [email protected] Subject: [NMusers] OMEGA-Block Dear NMusers, modelling a 2-compartmet model parameterized by CL, V1, VSS and Q, I got to a problem with which I don’t know how to deal with: After choosing my structural and statistic model (combined residual error model) I estimated the covariance matrix by including an OMEGA-BLOCK(4), which reduced the OFV by 15. The correlations between the parameters were all estimated to be minor (< 0.8). But when I model with a BLOCK(2) on VSS and V1, which I would expect to be positively correlated, the correlation is estimated to be -0.99. Additionally, the inclusion of BLOCK(2) does not significantly improve the OFV. So does it, after all, still make sense to include the BLOCK(2)? Generally, at which step of model-building would you recommend to test for parameter correlation? Thanking you in advance, Hauke ----------------------------- Hauke Rühs Apotheker Pharmazeutisches Institut - Klinische Pharmazie - An der Immenburg 4 53121 Bonn Tel: + 49-(0)228 73-5781 Fax: + 49-(0)228 73-9757 www.klinische-pharmazie.info
