Re: posthoc step

From: "Nick Holford" n.holford@auckland.ac.nz Subject: Re: [NMusers] posthoc step Date: Wed, December 8, 2004 10:32 pm Steve, I don't understand why you say: > When the prior variance was set to 4 Khat was estimated at 0.95 > These are similar to the NONMEM and SAS results when variance was 4. I wrote earlier: > The estimate of Khat for all methods remains stubbornly at 10 with SD of 2. i.e. the prior variance on K was 4. and Leonid wrote: > [K] goes up to 9.78 when you move OMEGA down to 4 I'ts not clear if Leonid means OMEGA is the variance of the prior or the SD of the prior. But whichever convention one assumes it is evident that we both get estimates of Khat very close to 10 and not 0.95. It looks like WinBUGS and SAS seem to think Khat is dominated by the data (simulated with K=1) whereas NONMEM seems to prefer the prior of 10 (SD=2). It appears to me that NONMEM has a better sense of the prior on K because as Leonid pointed out there is only 3 on one million chance that K=1. Nick -- Nick Holford, Dept Pharmacology & Clinical Pharmacology University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New Zealand email:n.holford@auckland.ac.nz tel:+64(9)373-7599x86730 fax:373-7556 http://www.health.auckland.ac.nz/pharmacology/staff/nholford/