limma (version 3.28.14)

qqt: 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, ...) 
qqf(y, df1, df2, ylim=range(y), main= "F Distribution 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.

df1

numerator degrees of freedom for the F-distribution.

df2

denominator degrees of freedom for the F-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

Value

x

theoretical quantiles of the t-distribution or F-distribution

y

the data sample, same as input y

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.

See Also

qqnorm

Examples

#  See also the lmFit examples

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