qqt {limma}R Documentation

Student's t Quantile-Quantile Plot

Description

Plots the quantiles of a data sample against the theoretical quantiles of a Student's t distribution.

Usage

qqt(y, df = Inf, ylim = range(y), main = "Student's t Q-Q Plot", 
    xlab = "Theoretical Quantiles", ylab = "Sample Quantiles", plot.it = TRUE, ...) 

Arguments

y a numeric vector or array containing the data sample
df degrees of freedom for the t-distribution. The default df=Inf represents the normal distribution.
ylim plotting range for y
main main title for the plot
xlab x-axis title for the plot
ylab y-axis title for the plot
plot.it whether or not to produce a plot
... other arguments to be passed to plot

Details

This function is analogous to qqnorm for normal probability plots. In fact qqt(y,df=Inf) is identical to qqnorm(y) in all respects except the default title on the plot.

Value

A list is invisibly returned containing the values plotted in the QQ-plot:

x theoretical quantiles of the t-distribution
y the data sample, same as input y

Author(s)

Gordon Smyth

See Also

qqnorm

Examples

#  See also the lmFit examples

y <- rt(50,df=4)
qqt(y,df=4)
abline(0,1)

[Package limma version 2.4.7 Index]