LPE (version 1.46.0)

iqr: 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.

Jain et. al. (2005) Rank-invariant resampling based estimation of false discovery rate for analysis of small sample microarray data, BMC Bioinformatics, Vol 6, 187.

See Also

lpe

Examples

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