animation (version 2.0-5)

sim.qqnorm: Simulation of QQ plots for the Normal distribution

Description

This demo shows the possible QQ plots created by random numbers generated from a Normal distribution so that users can get a rough idea about how QQ plots really look like.

Usage

sim.qqnorm(n = 20, last.plot, ...)

Arguments

n

integer: sample size

last.plot

an expression to be evaluated after the plot is drawn, e.g. expression(abline(0, 1)) to add the diagonal line

...

other arguments passed to qqnorm

Value

• NULL

Details

When the sample size is small, it is hard to get a correct inference about the distribution of data from a QQ plot. Even if the sample size is large, usually there are outliers far away from the straight line. Therefore, don't overinterpret the QQ plots.

See Also

qqnorm

Examples

oopt = ani.options(interval = 0.1, nmax = ifelse(interactive(), 
    100, 2))
par(mar = c(3, 3, 2, 0.5), mgp = c(1.5, 0.5, 0), tcl = -0.3)

sim.qqnorm(n = 20, last.plot = expression(abline(0, 
    1)))

## HTML animation pages
saveHTML({
    par(mar = c(3, 3, 1, 0.5), mgp = c(1.5, 0.5, 0), tcl = -0.3)
    ani.options(interval = 0.1, nmax = ifelse(interactive(), 
        100, 2))
    sim.qqnorm(n = 15, pch = 20, main = "")
}, img.name = "sim.qqnorm", htmlfile = "sim.qqnorm.html", ani.height = 500, 
    ani.width = 500, title = "Demonstration of Simulated QQ Plots", 
    description = c("This animation shows the QQ plots of random numbers", 
        "from a Normal distribution. Does them really look like normally", 
        "distributed?"))

ani.options(oopt)