Monte Carlo Simulations

Phoenix Certara Forums Modelling and Simulation
1

Dear All,

Currently I am performing my monte carlo simulations using Berkeley Madonna. Can someone tell me how I can do this with Phoenix NLME?

I don’t want to do a predictive check. I just want to use my population parameters + omegas to simulate say 500 Patients with different dosing schedules.

I am grateful for your help.

Best,

Joao

2

Hi Joao,
This is an exercice I always show and teach during the trainings.

You need to code your model with all parameters omega etc. now you want to map in the data that will tell the software about the desgin of your dose etc. you can map one single file telling about the ID/Dose or have dose in a separate sheet as usual.

Note that you dont need to specify the time grid template in advance since in your simulation table you can select a sequence of time e.g: seq(0,100,1)

you can have five different subjects with each having a different dosing schedule then in simulation/Predictive check you select 500 replicate which will be dismulation the 5 subjects 500 times and each time you have a different random sample from the Omega matrix. ( that is why it is called simulation /Pred check) it can be used for simulation or for predictive checks and in this case there is no data to compare to it is pure simulation)
in your table you can output the simualted concentraiton with error Cobs or whatever you call it and C ( ipred without error).

Hope this helps.

Samer

3

Dear Samer,

That is what I tried to do. However, it does not return any values. I may be doing something wrong. Unfortunately, I cannot send you my file. Would it be possible for you to post an example project file?

Best,

Joao

4

Hi Joao,
You can just post a project with your model with dummy value of parameters ?
no need to attach any data since it is simulation
Samer

5

Hello Samer,

I found the problem. Actually, there was no problem. I was looking at the Output “Table01” - And that is empty! The results of my simulations are on “Rawsimtbl01.csv”. Why is “Table01” empty, but the csv output not? Is this a bug?

Thanks,

Joao

6

it is not a bug simulation table are not read back to the gui since they can be giga bytes of data. depending on how you setup your data table01 might refer to a table for a simple mode run and not simulation table.

in the new version to be released later in the year you will get back the simulation table to a worksheet we have improved how we handle big data tables.

export rwasimtbl to disk and bring it back to phoenix and do the plot !

7

You are right. The table is 800 Mb. If I have to export it, then I will just deal with it with R.

Thanks