Could someone explain the variance-covariance matrix set-up of the random effects tab? I am new to population PK modeling and would like to use the Phoenix NLME interface.
I understand that the default setting is to select the diagonal covariance model that assumes all random effects are independent. My data showed that CL and V were highly correlated, but Ka was not correlated to any other parameter. How would I proceed from this point? I see there is an option to "split" or "break" the parameters, but it is not clear what this means.
Any help would be appreciated. Thanks!
