# Compute the distance-to-median statistic

### Description

Compute the distance-to-median statistic for the CV2 residuals of all genes

### Usage

1 |

### Arguments

`mean` |
A numeric vector of average counts for each gene. |

`cv2` |
A numeric vector of squared coefficients of variation for each gene. |

`win.size` |
An integer scalar specifying the window size for median-based smoothing. |

### Details

This function will compute the distance-to-median (DM) statistic described by Kolodziejczyk et al. (2015).
Briefly, a median-based trend is fitted to the log-transformed `cv2`

against the log-transformed `mean`

.
The DM is defined as the residual from the trend for each gene.
This statistic is a measure of the relative variability of each gene, after accounting for the empirical mean-variance relationship.
Highly variable genes can then be identified as those with high DM values.

### Value

A numeric vector of DM statistics for all genes.

### Author(s)

Jong Kyoung Kim, with modifications by Aaron Lun

### References

Kolodziejczyk AA, Kim JK, Tsang JCH et al. (2015).
Single cell RNA-sequencing of pluripotent states unlocks modular transcriptional variation.
*Cell Stem Cell* 17(4), 471–85.

### Examples

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