From: Rong Chen <*rongchenchn*>

Date: Sun, 7 May 2017 10:55:24 +0000 (UTC)

Hi Tingjie,I think this article could answer your question by indicating th=

e objective function used to estimate post hoc eta and how to reproduce the=

estimate process in R. There were R codes example of a one-compartment PK =

model with 3 etas to be estimated. Title: R-based reproduction of the =

estimation process hidden behind NONMEM® Part 1: first-order approxima=

tion. URL: http://dx.doi.org/10.12793/tcp.2015.23.1.1

Best wishes,Rong

From: "Guo, Tingjie" <t.guo

To: nmusers <nmusers

Sent: Friday, 5 May 2017, 20:17

Subject: [NMusers] Estimation method for ETAs with POSTHOC

Dear NMusers,

I have two questions about the mathematical details on POSTHOC estimation i=

n NONMEM. How does NONMEM actually do when doing POSTHOC ($EST METHOD=0 M=

AXEVEL=0) to get ETAs? I assume but not for sure there is an objective fu=

nction to be minimized, somewhat like:

Objective function = SUM(Yobs-Ypred)^2/sigma^2 + SUM=

(Para_i-Para_pop)^2/omega^2

Is there an objective function used in NONMEM when doing POSTHOC? If so, wh=

at is that function?

Secondly, if the answer to above is yes, let’s assume the real obje=

ctive function is the same as what I mentioned above. I wonder how (NONMEM =

does) to minimize this function? I am currently trying to do similar things=

in R/Python language. I tried Metropolis-Hasting algorithm and Simulated A=

nnealing algorithm, but with some technical problems. And the result was no=

t comparable with NONMEM as well. Can someone give me a direction for this?=

The more mathematically detailed the better.

Thanks!

Warm regards,

Tingjie

Received on Sun May 07 2017 - 06:55:24 EDT

Date: Sun, 7 May 2017 10:55:24 +0000 (UTC)

Hi Tingjie,I think this article could answer your question by indicating th=

e objective function used to estimate post hoc eta and how to reproduce the=

estimate process in R. There were R codes example of a one-compartment PK =

model with 3 etas to be estimated. Title: R-based reproduction of the =

estimation process hidden behind NONMEM® Part 1: first-order approxima=

tion. URL: http://dx.doi.org/10.12793/tcp.2015.23.1.1

Best wishes,Rong

From: "Guo, Tingjie" <t.guo

To: nmusers <nmusers

Sent: Friday, 5 May 2017, 20:17

Subject: [NMusers] Estimation method for ETAs with POSTHOC

Dear NMusers,

I have two questions about the mathematical details on POSTHOC estimation i=

n NONMEM. How does NONMEM actually do when doing POSTHOC ($EST METHOD=0 M=

AXEVEL=0) to get ETAs? I assume but not for sure there is an objective fu=

nction to be minimized, somewhat like:

Objective function = SUM(Yobs-Ypred)^2/sigma^2 + SUM=

(Para_i-Para_pop)^2/omega^2

Is there an objective function used in NONMEM when doing POSTHOC? If so, wh=

at is that function?

Secondly, if the answer to above is yes, let’s assume the real obje=

ctive function is the same as what I mentioned above. I wonder how (NONMEM =

does) to minimize this function? I am currently trying to do similar things=

in R/Python language. I tried Metropolis-Hasting algorithm and Simulated A=

nnealing algorithm, but with some technical problems. And the result was no=

t comparable with NONMEM as well. Can someone give me a direction for this?=

The more mathematically detailed the better.

Thanks!

Warm regards,

Tingjie

Received on Sun May 07 2017 - 06:55:24 EDT