animation (version 1.1-4)

sample.strat: Demonstration for stratified sampling...

Description

Demonstration for stratified sampling Every rectangle stands for a stratum, and the simple random sampling without replacement is performed within each stratum. The points being sampled are marked out (by red circles by default).

Usage

sample.strat(pop=ceiling(10 * runif(10, 0.5, 1)), size=ceiling(pop *
    runif(length(pop), 0, 0.5)), p.col=c("blue", "red"), p.cex=c(1, 3),
    ...)

Arguments

pop

a vector for the size of each stratum in the population.

size

a corresponding vector for the sample size in each stratum (recycled if necessary).

p.col,p.cex

different colors /magnification rate to annotate the population and the sample

...

other arguments passed to rect to annotate the ``strata''

Value

• None (invisible `NULL').

References

Cochran, W G (1977) Sampling Techniques, Wiley, ISBN 0-471-16240-X http://animation.yihui.name/samp:stratified_sampling

See Also

sample, sample.simple, sample.cluster, sample.ratio, sample.system

Examples

oopt = ani.options(interval = 1, nmax = 30)
op = par(mar = rep(1, 4), lwd = 2)
sample.strat(col = c("bisque", "white"))
par(op)
# HTML animation page
ani.options(ani.height = 350, ani.width = 500, outdir = getwd(), nmax = 30,
interval = 1, title = "Demonstration of the stratified sampling",
description = "Every rectangle stands for a stratum, and the simple
random sampling without replacement is performed within each stratum.")
ani.start()
par(mar = rep(1, 4), lwd = 2)
sample.strat(col = c("bisque", "white"))
ani.stop()
ani.options(oopt)