animation (version 1.1-4)

sample.system: Demonstration for systematic sampling...

Description

Demonstration for systematic sampling The whole sample frame is denoted by a matrix (nrow * ncol) in the plane, and the sample points with equal intervals are drawn out according to a random starting point. The points being sampled are marked by red circles.

Usage

sample.system(nrow=10, ncol=10, size=15, p.col=c("blue", "red"),
    p.cex=c(1, 3))

Arguments

nrow

the desired number of rows of the sample frame.

ncol

the desired number of columns of the sample frame.

size

the sample size.

p.col,p.cex

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

Value

• None (invisible `NULL').

References

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

See Also

sample, sample.simple, sample.cluster, sample.ratio, sample.strat

Examples

oopt = ani.options(interval = 1, nmax = 30)
op = par(mar = rep(1, 4), lwd = 2)
sample.system()
par(op)

# HTML animation page
ani.options(ani.height = 350, ani.width = 500, outdir = getwd(), nmax = 30,
interval = 1, title = "Demonstration of the systematic sampling",
description = "Sampling with equal distances.")
ani.start()
par(mar = rep(1, 4), lwd = 2)
sample.system()
ani.stop()
ani.options(oopt)