Bill, Is it really an eta you want, or is this rather solved by different error models for the different machines?
If still want etas, one way would be to model in the same way as IOV. In the case of intermachine-variability you would have to assume the variability between all machines are the same... Or would you rather assume interindividual variability is different with different machine, and you then would want one eta for TH(X) for every machine...? It depends on what you mean by different slope every day, regarding on what your experiments like, but calibration differences should perhaps be taken care of by looking into your error model, eta on epsilon for starters... Without knowing your structure of data, a short example of IOV-like variability would be: MA1=0 MA2=0 IF(MACH=1)MA1=1 IF(MACH=2)MA2=1 ;Intermachine variability: ETAM = MA1*ETA(Y)+MA2*ETA(Z) PAR= TH(X) *EXP(ETA(X)+ETAM) $OMEGA value1 $OMEGA BLOCK(1) value2 $OMEGA BLOCK(1) same /Johan _________________________________________ Johan Wallin, M.Sci./Ph.D.-student Pharmacometrics Group Div. of Pharmacokinetics and Drug therapy Uppsala University _________________________________________ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Denney, William S. Sent: den 15 oktober 2008 14:39 To: nmusers@globomaxnm.com Subject: [NMusers] More Levels of Random Effects Hello, I'm trying to build a model where I need to have ETAs generated on separately for the ID and another variable (MACH). What I have is a PD experiment that was run on several different machines (MACH). Each machine appears to have a different slope per day and a different calibration. I still need to keep some ETAs on the ID column, so I can't just assign MACH=ID. I've heard that there are ways to do similar to this, but I have been unable to find examples of how to set etas to key off of different columns. Thanks, Bill Notice: This e-mail message, together with any attachments, contains information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New Jersey, USA 08889), and/or its affiliates (which may be known outside the United States as Merck Frosst, Merck Sharp & Dohme or MSD and in Japan, as Banyu - direct contact information for affiliates is available at http://www.merck.com/contact/contacts.html) that may be confidential, proprietary copyrighted and/or legally privileged. It is intended solely for the use of the individual or entity named on this message. If you are not the intended recipient, and have received this message in error, please notify us immediately by reply e-mail and then delete it from your system.
