Choose different residual error structure

Phoenix Certara Forums Modelling and Simulation
1

Hi all,

I fitted a 2 compartment model to a set of data (only one subject) using different residual error structures. Please see the phoenix project attached.

I compared the Ind DV vs IPRED; lnd DV, IPRED vs IVAR (y is logarithmic scale); lnd IWRES vs IPRED; and Ind IWRES vs IVAR. I also gave a score to each structure for each figure (score 1 means the best, score 3 means the worst). Please see the excel attached. Which residual error structure is the best one?

Thank you!

LLLi

Exercise 22 one subject.phxproj (927 KB)score.xlsx (8.11 KB)

2

I would personally go with mixed, it has the lowest AIC of the 3 models and generally the best residual plots.

I suggest you take another look at Ind IWRES vs IPRED, since for mixed there are no points outside the 2 sd lines and generally are closer to the centre line than additive or indeed multiplicatve alone

Simon