qqt {limma} | R Documentation

## Student's t or Fisher's F 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`

### 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 or F-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 3.50.3 Index]