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]