![Reduced models: A way to choose initial parameters for a mixed model](https://blogs.sas.com/content/iml/files/2017/01/ProgrammingTips-2.png)
This article describes how to obtain an initial guess for nonlinear regression models, especially nonlinear mixed models. The technique is to first fit a simpler fixed-effects model by replacing the random effects with their expected values. The parameter estimates for the fixed-effects model are often good initial guesses for the