Zhao, For more details you can look at Nonmem help and manuals. POSTHOC step of FO and MAXEVAL=0 of FOCE will do exactly the same computations (given the population parameters, will compute individual parameters and predictions). INTERACTION options allows a more precise interpretation of the error model (from help: with INTER option, "The dependence on etas of the model for intra-individual random error is preserved in the computation of the objective function" while without it, the program "set etas to 0 during the computation of the model for intraindividual random error") Leonid
-------------------------------------- Leonid Gibiansky, Ph.D. President, QuantPharm LLC web: www.quantpharm.com e-mail: LGibiansky at quantpharm.com tel: (301) 767 5566 On 1/6/2014 6:53 AM, 赵赵 wrote: > Dear Dr Leonid， > > Thanks so much! Your answer gave me a very clear direction of what to do > next. Still, I just wonder the reason,the principle behind it. Would you > please give me a further explanation? > > Thanks in advance > > Regards, > Zhao > > > Date: Sun, 5 Jan 2014 10:56:17 -0500 > > From: [email protected] > > To: [email protected]; [email protected] > > Subject: Re: [NMusers] Question: FO VS. FOCE VS. FOCE-INTER in > POSTHOC 2014-1-3 > > > > Zhao, > > > > For MAXEVAL=0, FOCE and FO should provide identical results (POSTHOC is > > needed for FO; for FOCE it is not necessary but you can use it as well). > > Concerning INTER, it should be used in all cases except when the error > > is purely additive (and you can use it even for additive error, this > > should not affect your solution). So if you need POSTHOC run, the > > recommendation is to use > > > > $ESTIMATION MAXEVAL=0 METHOD=1 INTER NOABORT POSTHOC > > > > in all cases. For external validation, VPC-style diagnostics (as well as > > regular model diagnostic plots) would be preferable to the overall > > measures like MPE or RMSE that are more or less useless in identifying > > the direction of the bias (if you have any differences with the > > literature models). > > > > Leonid > > > > > > -------------------------------------- > > Leonid Gibiansky, Ph.D. > > President, QuantPharm LLC > > web: www.quantpharm.com > > e-mail: LGibiansky at quantpharm.com > > tel: (301) 767 5566 > > > > > > > > On 1/4/2014 9:31 PM, 赵赵 wrote: > > > Dear all, > > > > > > First of all, I wanna say HAPPY NEW YEAR to you guys. Best Wishes in > > > this very beginning day of the "Horse Year"(Chinese calendar lol ) > > > > > > Well,as titled, here is the question: > > > > > > I'm now doing external validation of the PPK models pubished before by > > > other groups with my own data. Ｉfind extreme differences in MPE(mean > > > prediction error), RMSE(root of mean squared prediction error) and > so on > > > while using different estimation methods like FO, FOCE, or FOCE-INTER, > > > especially the one with interaction from the former 2. > > > > > > I do understand the diversity in these 3 methods. But how much is the > > > influence as to POSTHOC in external validation. For example: > > > > > > $ESTIMATION MAXEVAL=0 METHOD=1 NOABORT POSTHOC > > > > > > Could anybody explain to me and clarify the problem? > > > > > > Great thanks! > > > > > > Yours > > > > > > Zhao Chenyan > > > > > > Department of Clinical Pharmacy, Huashan Hospital, Fudan University, > > > Shanghai, P.R.China > > >
