Normalization of cDNA microarray data
Author(s)
Smyth, GK; Speed, T;
Details
Publication Year 2003-12,Volume 31,Issue #4,Page 265-273
Journal Title
METHODS
Publication Type
Journal Article
Abstract
Normalization means to adjust microarray data for effects which arise from variation in the technology rather than from biological differences between the RNA samples or between the printed probes. This paper describes normalization methods based on the fact that dye balance typically varies with spot intensity and with spatial position on the array. Print-tip loess normalization provides a well-tested general purpose normalization method which has given good results on a wide range of arrays. The method may be refined by using quality weights for individual spots. The method is best combined with diagnostic plots of the data which display the spatial and intensity trends. When diagnostic plots show that biases still remain in the data after normalization, further normalization steps such as plate-order normalization or scale-normalization between the arrays may be undertaken. Composite normalization may be used when control spots are available which are known to be not differentially expressed. Variations on loess normalization include global loess normalization and two-dimensional normalization. Detailed commands are given to implement the normalization techniques using freely available software. (C) 2003 Elsevier Science (USA). All rights reserved.
Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
Keywords
GENES
Terms of Use/Rights Notice
Refer to copyright notice on published article.


Creation Date: 2003-12-01 12:00:00
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