## Inter-quartile range

### Description

Finds inter-quartile range of the data = {75th percentile - 25th percentile}.

### Usage

iqr(x)

### Arguments

`x` |
x is a vector for which IQR has to be found. |

### Value

Returns a numeric value representing the difference of 75th percentile
and 25th percentile of the vector. It is used for normalization across
the chips - basic assumption is that net differential expression of
the middle half of the genes in microarray experiment is zero, which
is conservative assumption as typically only 5-10
differential expression.

### References

J.K. Lee and M.O.Connell(2003). *An S-Plus library for the analysis of differential expression*. In The Analysis of Gene Expression Data: Methods and Software. Edited by G. Parmigiani, ES Garrett, RA Irizarry ad SL Zegar. Springer, NewYork.

Jain et. al. (2003) *Local pooled error test for identifying
differentially expressed genes with a small number of replicated microarrays*, Bioinformatics, 1945-1951.

### See Also

`lpe`

### Examples

library(LPE)
# Loading the LPE library
iqr(1:5)

[Package

*LPE* version 1.1.5

Index]