tmixture {limma} | R Documentation |

## Estimate Scale Factor in Mixture of t-Distributions

### Description

This function estimates the unscaled standard deviation of the log fold change for differentially expressed genes.
It is called by the function `ebayes`

and is not intended to be called by users.

### Usage

tmixture.vector(tstat,stdev.unscaled,df,proportion,v0.lim=NULL)
tmixture.matrix(tstat,stdev.unscaled,df,proportion,v0.lim=NULL)

### Arguments

`tstat` |
numeric vector or matrix of t-statistics |

`stdev.unscaled` |
numeric matrix conformal with `tstatf` containing the unscaled standard deviations for the coefficient estimators |

`df` |
numeric vector giving the degrees of freedom associated with `tstat` |

`proportion` |
assumed proportion of genes which are differentially expressed |

`v0.lim` |
numeric vector of length 2, assumed lower and upper limits for the estimated unscaled standard deviation |

### Details

The values in each column of `tstat`

are assumed to follow a mixture of an ordinary t-distribution, with mixing proportion `1-proportion`

, and `(v0+v1)/v1`

times a t-distribution, with mixing proportion `proportion`

.
Here `v1=stdev.unscaled^2`

and `v0`

is the value to be estimated.

### Value

Numeric vector of length equal to the number of columns of `tstat`

and `stdev.unscaled`

.

### Author(s)

Gordon Smyth

### See Also

`ebayes`

[Package

*limma* version 2.4.7

Index]