simpleboot (version 0.1-4)

pairs.boot: Two sample bootstrap.

Description

pairs.boot is used to bootstrap a statistic which operates on two samples and returns a single value. An example of such a statistic is the correlation coefficient (i.e. cor). Resampling is done pairwise, so x and y must have the same length (and be ordered correctly). One can alternatively pass a two-column matrix to x.

Usage

pairs.boot(x, y = NULL, FUN, R, student = FALSE, M, weights = NULL, ...)

Arguments

x

Either a vector of numbers representing the first sample or a two column matrix containing both samples.

y

If NULL it is assumed that x is a two-column matrix. Otherwise, y is the second sample.

FUN

The statistic to bootstrap. If x and y are separate vectors then FUN should operate on separate vectors. Similarly, if x is a matrix, then FUN should operate on two-column matr

R

The number of bootstrap replicates.

student

Should we do a studentized bootstrap? This requires a double bootstrap so it might take longer.

M

If student is set to TRUE, then M is the number of internal bootstrap replications to do.

weights

Resampling weights.

...

Other (named) arguments that should be passed to FUN.

Value

• An object of class "uclaboot", which is almost identical to the regular "boot" object. For example, the boot.ci function can be used on this object.

Examples

set.seed(1)
x <- rnorm(100)
y <- 2 * x + rnorm(100)
boot.cor <- pairs.boot(x, y, FUN = cor, R = 1000)
boot.ci(boot.cor)

## With weighting
set.seed(20)
w <- (100:1)^2
bw <- pairs.boot(x, y, FUN = cor, R = 5000, weights = w)
boot.ci(bw, type = c("norm", "basic", "perc"))