title: Foundation for nonlinear models with thresholds for longitudinal data.
abstract: Threshold models first appeared in the literature nearly half a century ago. Threshold segments have been added to many commonly used forms of models from linear models and generalized linear models through mixed models for the analysis of cross-sectional data. Nonlinear models with thresholds for cross-sectional data are less prevalent in the literature. Nonlinear models with thresholds for longitudinal data are new. The historical developments leading to this point are reviewed as a means of introducing terms necessary for discussing features of these newer models. Nonlinear models for longitudinal data with thresholds are presented and discussed.
authors: FDA Center for Veterinary Medicine, Division of Biometrics and Production Drugs, Rockville, Maryland 20855, USA.
authors: M J
authors: MJ
authors: Bartholomew
mesh_terms: D000465:Algorithms; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D017711:Nonlinear Dynamics; D011153:Population; D012044:Regression Analysis