Hi, I am trying to build a model to fit a plasma conc for a drug after a single dose. I created a base model with two compartments and Tlag. I got a reasonable fit, but I still get very high shrinkage in one of the Pk parameters (Vd)
Would you please take a look to see if there is any way to decrease the shrinkage value?
I have attached the model below.
Thanks
New Project 10_22.phxproj (881 KB)
Hi Amashehri,
I’m not sure if there is anything you can to decrease the shrinkage; it is a diagnostic that tells you the data does not have enough information to estimate random effects on this parameter. I think with the second compartment parameters identifiability can be an issue, since even when you remove random effects for v2, shrinkage is still a little high for CL2
I don’t think considering covariates would help, but I’d be interested to hear others experiences.
Thanks Simon for your reply
How did you end up dealing with high shrinkage values? The shrinkage value of one of my parameters was not high before the addition of the covariable model, but after the addition of the covariable model, the shrinkage value of the parameter was close to 0.98. Do you have any suggestions?