has part fixed effect model random effect model statistical model mixed effect model Orlaith Burke A mixed model is a statistical model containing both fixed effects and random effects. These models are useful in a wide variety of disciplines in the physical, biological and social sciences. They are particularly useful in settings where repeated measurements are made on the same statistical units (longitudinal study), or where measurements are made on clusters of related statistical units. Because of their advantage in dealing with missing values, mixed effects models are often preferred over more traditional approaches such as repeated measures ANOVA. Alejandra Gonzalez-Beltran PRS: this is a stub and more work is needed to reconcile conflicting definitions Philippe Rocca-Serra adapted from wikipedia requires discussion