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?