SimBiology

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I'm trying to use the simbiology app to fit data with a simbiology model. The problem is that between the data groups there is a independent variable (AHL) that changes between them (image 1). When the data was imported I defined the AHL row as a covariate (which I think is right) as seen in the image 1. The problem is that when I go to the data fit program in the simbiology app, at the part when all the other variables are defined (image 2), there is no option to define this AHL row as a covariate that needs to be linked to a parameter of the simbiology model (this, as shown in the image can be done for the group, independent and dependent type of variables). Is there a way I can do to define the AHL parameter so that it changes between data groups in fit data program of the simbiology app?

If I'm fitting using lsqnonlin, is there a matlab script function that returns the group number? The idea is to allow use of covariates without having to add false dose columns in the dataset. I could use the group variable to look up parameters in a table, and use assignment rules to set parameters. So I could use covariates to set some parameters while fitting other. As in fitting a PK model with some data, and then using the typical parameter values plus covariate rules to set PK parameter when I do a PD fit using data from another trial/dataset. One could (perhaps) use the following script to set parameter parA Repeat assignment rule for parA is parA = getparA(); getparA.m % [parA] = getparA(); % returns parA gp = getgroupvar(); % This is the function I'm asking about if ~exist(parAdata) parAdata = dataset('parAdata.xlsx'); % columns are subject and parA values end [~,idx]=ismember(gp,parAdata(:,1)); idx(idx==0)=[]; parA = parAdata(idx,2); This would allow one to set any number of parameter values without modifying the dataset. Alternately I could create a copy of the subject column (dummy_subj) and create a species subj_number in the model. Then dummy_subj could be used to put a dose in subj_number, and I could do the same lookup approach. The point is, once one does (for example) a PK fit to get individual parameters (either with nlmefit or lsqnonlin), there are a lot of machinations needed to actually USE the parameter values in subsequent fits. Also, nlmefit, one can add covariate effect when one is fitting a specific parameter. But (my understading is that if one unclicks the "estimate" tic box so that the parameter is not fitted, then this turns off the covariate effect as well.

In SimBiology I have constructed a simple 2 Compartment Model to describe drug distribution over a set time course. The Model uses 6 parameters. I have a set of 11 individual data sets for the drug, however they are taken from different disease stages (early & late) which can be quantified as the "Time stage of Disease". Previous literature has stated a relationship between the stage of the disease and drug accumulation. However the specific relationship is not known. How do I incorporate the stage of disease as a covariate into my model? I'm unclear how to specify a relationship between the stage and the parameter, most literature says to use a NLME model but again I'm unclear about the implementation of this