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();
gp = getgroupvar();
parAdata = dataset('parAdata.xlsx');
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.