Regression splines(parametric) Smoothing splines (nonparametric The piecewise constant model o To understand splines,we will gradually build up a piecewise model,starting at the simplest one:the piecewise constant model o First,we partition the range of z into K+1 intervals by choosing K points called knots o For our example involving bone mineral density,we will choose the tertiles of the observed ages Patrick Breheny STA 621:Nonparametric StatisticsIntroduction Regression splines (parametric) Smoothing splines (nonparametric) The piecewise constant model To understand splines, we will gradually build up a piecewise model, starting at the simplest one: the piecewise constant model First, we partition the range of x into K + 1 intervals by choosing K points {ξk} K k=1 called knots For our example involving bone mineral density, we will choose the tertiles of the observed ages Patrick Breheny STA 621: Nonparametric Statistics