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Posts Tagged ‘mixed-effects’

Just released from Stata Press: Multilevel and Longitudinal Modeling Using Stata, Fourth Edition

Stata Press is pleased to announce the release of Multilevel and Longitudinal Modeling Using Stata, Volumes I and II, Fourth Edition by Sophia Rabe-Hesketh and Anders Skrondal. This book debuted on the top 10 list for Kindle’s new releases for Probability & Statistics and consistently stayed there for weeks. This book was also on the top 10 list for Kindle’s new releases in Mathematics, competing with many other books. Read more…

Nonlinear multilevel mixed-effects models

You have a model that is nonlinear in the parameters. Perhaps it is a model of tree growth and therefore asymptotes to a maximum value. Perhaps it is a model of serum concentrations of a drug that rise rapidly to a peak concentration and then decay exponentially. Easy enough, use nonlinear regression ([R] nl) to fit your model. But … what if you have repeated measures for each tree or repeated blood serum levels for each patient? You might want to account for the correlation within tree or patient. You might even believe that each tree has its own asymptotic growth. You need nonlinear mixed-effects models—also called nonlinear hierarchical models or nonlinear multilevel models. Read more…