| DemoNull {gps} | R Documentation |
Demonstrate the null space of P-splines
Description
Cubic P-splines set up with non-uniform B-splines and a 2nd order standard or general difference penalty are fitted to observations simulated from y = x. Should the resulting standard or general P-splines have the correct null space, the limiting fit at \lambda = +\infty will be a straight line regardless of knot locations. In this demo, non-uniform knots from different distributions (primarily Beta distributions with varying shape parameters) are attempted. Results show that standard P-splines have an incorrect and unpredictable limiting behavior that is sensitive to knot locations, whereas general P-splines have a correct and consistent limiting behavior.
Usage
DemoNull(n, k, gps = FALSE)
Arguments
n |
number of simulated observations from |
k |
number of interior knots to place. |
gps |
if TRUE, fit general P-splines; if FALSE, fit standard P-splines. |
Value
This function has no returned values.
Author(s)
Zheyuan Li zheyuan.li@bath.edu
Examples
require(gps)
## standard P-splines
DemoNull(n = 100, k = 10, gps = FALSE)
## general P-splines
DemoNull(n = 100, k = 10, gps = TRUE)