title: A comparison of normalization methods for high density oligonucleotide array data based on variance and bias.
abstract: BACKGROUND
  When running experiments that involve multiple high density oligonucleotide arrays, it is important to remove sources of variation between arrays of non-biological origin. Normalization is a process for reducing this variation. It is common to see non-linear relations between arrays and the standard normalization provided by Affymetrix does not perform well in these situations.
  
  
  RESULTS
  We present three methods of performing normalization at the probe intensity level. These methods are called complete data methods because they make use of data from all arrays in an experiment to form the normalizing relation. These algorithms are compared to two methods that make use of a baseline array: a one number scaling based algorithm and a method that uses a non-linear normalizing relation by comparing the variability and bias of an expression measure. Two publicly available datasets are used to carry out the comparisons. The simplest and quickest complete data method is found to perform favorably.
  
  
  BACKGROUND
  Software implementing all three of the complete data normalization methods is available as part of the R package Affy, which is a part of the Bioconductor project http://www.bioconductor.org.
  
  
  BACKGROUND
  Additional figures may be found at http://www.stat.berkeley.edu/~bolstad/normalize/index.html
authors.affiliation: Group in Biostatistics, University of California, Berkeley, CA 94720, USA. bolstad@stat.berkeley.edu
authors.forename: B M
authors.initials: BM
authors.lastname: Bolstad
authors.forename: R A
authors.initials: RA
authors.lastname: Irizarry
authors.forename: M
authors.initials: M
authors.lastname: Astrand
authors.forename: T P
authors.initials: TP
authors.lastname: Speed
mesh_terms: D000465:Algorithms; D002138:Calibration; D008957:Models, Genetic; D015335:Molecular Probes; D017711:Nonlinear Dynamics; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D011786:Quality Control; D017422:Sequence Analysis, DNA / Q000379:methods* / Q000592:standards; D013269:Stochastic Processes
chemical_list: D015335:Molecular Probes