Epsilon Shrinkage NaN

Hello! I’m getting an epsilon shrinkage of NaN and I’m not sure how to best rectify this. The model is a simple one compartment with first order elimination & absorption and the data I’m fitting includes includes 3 robust Ph1 studies as well as some sparse Ph2 data. Of note, when I fit only the robust data I do get an actual value for epsilon shrinkage. Any ideas would be greatly appreciated.

Do you have any subjects with just a single observation?

Yes I have 3 subjects who only have 1 observation. I just tried fitting with those 3 subjects removed and it does still result in an epsilon shrinkage of NaN. I will say the only reason I noticed was because I can’t use the GOF plot functions when epsilon shrinkage is NaN. It doesn’t seem to impact anything else (that I can tell).

I’m not sure if this is helpful - but when I remove the study with only steady state data (where I have to use the II,SS,ADDL inputs) the problem resolves.

In the original fit, were any of the individual (weighted) residuals NaN or Inf? If not, could you please try wresiduals(yourfit, LaplaceI()) and see if there are any NaNs or Infs?

Just checked for both the original fit and the above suggested. The only instances of NaN occur at dosing records (EVID==1) for both scenarios. Otherwise, there are no instances of NaN or Inf .