Re: Problem of STS in NONMEM

> On Dec 22, 2015, at 5:32 AM, Anyue Yin <[email protected]> wrote: > > Dear all, > > Thanks for replying me. > > I am trying to carry out the first stage of Standard Two Stage estimation > method in NONMEM (i.e. estimate individual parameter by ID). For the sake of > argument, let's assume that I have a data file which includes 10 subjects (ID > from 1 to 10). Now I wish to estimate individual parameter by fitting each > individual data, so I will be able to get 10 individual parameter estimates. > But I found that these 10 individual parameter estimates were all around the > initial value what I assigned to the THETA. For example, if I assign 20 to > the initial value of THETA, then these 10 parameter estimates are all around > 20. If I assign 30, then all around 30... It looks like NONMEM uses initial > value of THETA as prior to estimate individual parameters. What I expect is > to estimate individual parameters by ID, as if these 10 subjects are > separated into 10 data file and estimate 10 times to get each result. So the > key point of my question is individual parameter estimation by the first > stage of STS in NONMEM. Thank you very much. > > Sincerely, > Anyue > >> On Tue, Dec 22, 2015 at 5:33 PM, Mats Karlsson <[email protected]> >> wrote: >> Dear Anyue, >> >> >> >> I don’t know what you mean by “the individual parameter estimate changed if >> I change the initial value of THETA” >> >> >> >> If you mean that individual ETA estimates change, that is expected when you >> change THETA. For CL and V to be the same, ETA need to change when THETA >> change. It may be that you are at local minima for EBEs. You may want to add >> MCETA=1000 on the $EST line in order to test more initial estimates. I would >> use MAXEVAL=0, not MAXEVAL=9999. Possibly I would use MAXEVAL=9999 after >> having fixed $OMEGA parameters to the high values you use now. >> >> >> >> Best regards, >> >> Mats >> >> >> >> >> >> Mats Karlsson, PhD >> >> Professor of Pharmacometrics >> >> >> >> Dept of Pharmaceutical Biosciences >> >> Faculty of Pharmacy >> >> Uppsala University >> >> Box 591 >> >> 75124 Uppsala >> >> >> >> Phone: +46 18 4714105 >> >> Fax + 46 18 4714003 >> >> www.farmbio.uu.se/research/researchgroups/pharmacometrics/ >> >> >> >> From: [email protected] [mailto:[email protected]] On >> Behalf Of Mills, Richard >> Sent: Tuesday, December 22, 2015 8:54 AM >> To: Anyue Yin; [email protected] >> Subject: RE: [NMusers] Problem of STS in NONMEM >> >> >> >> Hi Anyue, >> >> >> >> You need to amend MAXEVAL=0 in $EST (I suggest MAXEVAL=9999) in order to >> allow estimation. >> >> >> >> Kind regards, >> >> Richard >> >> Richard Mills PhD >> Senior Scientist, PKPDM&S >> >> <image001.jpg> >> >> >> >>