qqnorm {base}R Documentation

Quantile-Quantile Plots

Description

qqnorm produces a normal QQ plot of the values in y. qqline adds a line to a normal quantile-quantile plot which passes through the first and third quartiles.

qqplot produces a QQ plot of two datasets.

Graphical parameters may be given as arguments to qqnorm, qqplot and qqline.

Usage

qqnorm(y, ylim, main = "Normal Q-Q Plot", xlab = "Theoretical Quantiles",
       ylab = "Sample Quantiles", plot.it = TRUE, ...)
qqline(y, ...)
qqplot(x, y, plot.it = TRUE, xlab = deparse(substitute(x)),
       ylab = deparse(substitute(y)), ...)

Arguments

x The first sample for qqplot.
y The second or only data sample.

Value

For qqnorm and qqplot, a list with components
x The x coordinates of the points that were/would be plotted
y The corresponding y coordinates

See Also

ppoints.

Examples

y <- rt(200, df = 5)
qqnorm(y); qqline(y, col = 2)
qqplot(y, rt(300, df = 5))
data(precip)
qqnorm(precip, ylab = "Precipitation [in/yr] for 70 US cities")
[Package Contents]