  Similar to variable selection in the linear regression model, selecting
significant components in the popular additive regression model is of great
interest. However, such components are unknown smooth functions of independent
variables, which are unobservable. As such, some approximation is needed. In
this paper, we suggest a combination of penalized regression spline
approximation and group variable selection, called the lasso-type spline method
(LSM), to handle this component selection problem with a diverging number of
strongly correlated variables in each group. It is shown that the proposed
method can select significant components and estimate nonparametric additive
function components simultaneously with an optimal convergence rate
simultaneously. To make the LSM stable in computation and able to adapt its
estimators to the level of smoothness of the component functions, weighted
power spline bases and projected weighted power spline bases are proposed.
Their performance is examined by simulation studies across two set-ups with
independent predictors and correlated predictors, respectively, and appears
superior to the performance of competing methods. The proposed method is
extended to a partial linear regression model analysis with real data, and
gives reliable results.
