Central to the idea of variance components models is the idea of fixed and random effects. Each effect in a variance components model must be classified as either a fixed or a random effect. Fixed ...

The MODEL statement names a single dependent variable and the fixed effects, which determine the X matrix of the mixed model (see the "Parameterization of Mixed Models" section for details). The ...

Rated as one of the top ten journals in healthcare administration, Medical Care is devoted to all aspects of the administration and delivery of healthcare. This scholarly journal publishes original, ...

Although fixed-effects models for panel data are now widely recognized as powerful tools for longitudinal data analysis, the limitations of these models are not well known. We provide a critical ...