chapter  3
Penalized Splines as Mixed Linear Models
Pages 22

This chapter’s purpose is to introduce penalized splines, show how they can be represented as mixed linear models, and emphasize some features of mixed-linear-model theory as applied to penalized splines. It considers only penalized splines for estimating a one-dimensional function of a single variable, y = f (x), i.e., scatterplot smoothing. Later chapters consider additive models with multiple x variables and spatial and other non-additive models in more than one dimension.