Hi,

I need to start leveraging the PML language to properly setup my model. I write up my equations with concentration. However, when WinNonlin converts my model the equations use amounts. I did a small test comparing the abundance formulation with my equations noticed when i convert my graphical model to a text version.

I am getting very different answers between the too models. Now the difference between the rate constants can be attributed to a difference in units. The volume should be the same though and this is what has me alarmed.

I am not sure handles the number for the error term (graphics vs text ), but that is really the only thing I can think of that could drive the difference.

The reason why I want to write it in this fashion is I am looking to do something similar to the PML school lesson on metabolites. They use MM kinetics which uses concentration. This should be ok but I am a bit concerned about the difference answers using the two modes.

I have attached the workbook.

Any help would be great

#### Attached Files

**Edited by mjPK, 21 November 2023 - 03:40 PM.**