lines.saddle.distn {boot} | R Documentation |
This function adds a line corresponding to a saddlepoint density or distribution function approximation to the current plot.
lines.saddle.distn(x, dens=TRUE, h=function(u) u, J=function(u) 1, npts=50, lty=1, ...)
x |
An object of class "saddle.distn" representing a saddlepoint approximation
to a distribution.
|
dens |
A logical variable indicating whether the saddlepoint density (TRUE ; the
default) or the saddlepoint distribution function (FALSE ) should be plotted.
|
h |
Any transformation of the variable that is required. Its first argument must be the value at which the approximation is being performed and the function must be vectorized. |
J |
When dens=T this function specifies the Jacobian for any transformation
that may be necessary. The first argument of J must the value at which
the approximation is being performed and the function must be vectorized.
If h is supplied J must also be supplied and both must have the
same argument list.
|
npts |
The number of points to be used for the plot. These points will be evenly spaced over the range of points used in finding the saddlepoint approximation. |
lty |
The line type to be used. |
... |
Any additional arguments to h and J .
|
The function uses smooth.spline
to produce the saddlepoint curve. When
dens=T
the spline is on the log scale and when dens=F
it is on the probit
scale.
sad.d
is returned invisibly.
A line is added to the current plot.
Davison, A.C. and Hinkley, D.V. (1997) Bootstrap Methods and Their Application. Cambridge University Press.
## does not work: cannot find the saddle distn library(modreg) # for smooth.spline # In this example we show how a plot such as that in Figure 9.9 of # Davison and Hinkley (1997) may be produced. Note the large number of # bootstrap replicates required in this example. expdata <- rexp(12) vfun <- function(d,i) { n <- length(d) (n-1)/n*var(d[i]) } exp.boot <- boot(expdata,vfun,R=9999) exp.L <- (expdata-mean(expdata))^2-exp.boot$t0 exp.tL <- linear.approx(exp.boot,L=exp.L) hist(exp.tL,nclass=50,prob=T) exp.t0 <- c(0,sqrt(var(exp.boot$t))) exp.sp <- saddle.distn(A=exp.L/12,wdist="m", t0=exp.t0) # The saddlepoint approximation in this case is to the density of # t-t0 and so t0 must be added for the plot. lines(exp.sp,h=function(u,t0) u+t0, J=function(u,t0) 1, t0=exp.boot$t0)