Hi Dave,

Thanks for the response. I think I wasn't explaining my situation correctly.

I have run the degradation script and have the common slope/different intercept parameters. I also have have the projected expiry based on the ICH limits, etc., from that pooled model.

I'm wanting to go in the opposite direction. Say, for example, that I have a lower spec limit of 1 mg/mL...and I want to know - based on the common slope *AND *accounting for the p=0.25 significance AND the 95%CI of the model - what my starting concentration would need to be for the model confidence interval to not drop below 1 mg/mL at a certain timepoint. I can get the answer by brute force...but I'm assuming that there's a better approach to doing this. For example, is it possible to save the model describing the lower 95%CI of the pooled fit and then do an inverse prediction, etc.?

Sorry I didn't go into more detail at first.

Chris