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SUMMARY:Wolfgang Huber from the EBI will be talking on the vsn method. - W
 olfgang Huber\, European Bioinformatics Institute\, Wellcome Trust Genome 
 Campus
DTSTART:20080407T131500Z
DTEND:20080407T121500Z
UID:TALK11377@talks.cam.ac.uk
CONTACT:Dr N Karp
DESCRIPTION:This is a bonus talk to the bioinformatics journal club due to
  the opportunity of Wolfgang Huber coming to speak. Dr Wolfgang Huber from
  the European Bioinformatics Institute\, Hinxton will be speaking about th
 e vsn method he developed to simultaneously stabilise the variance and cal
 ibrate microarray data. The Huber group develops mathematical and statisti
 cal methods for the understanding of functional genomics data.\n\nPaper de
 tails: Huber W.\, Von Heydebreck A.\, Sültmann H.\, Poustka A. and Vingro
 n M. (2002)  Variance stabilization applied to microarray data calibration
  and to the quantification of differential expression. ioinformatics 18: s
 uppl. 1 (2002)\, S96-S104.\n\nPaper abstract: We introduce a statistical m
 odel for microarray gene expression data that comprises data calibration\,
  the quantification of differential expression\, and the quantification of
  measurement error. In particular\, we derive a transformation h for inten
 sity measurements\, and a difference statistic Deltah whose variance is ap
 proximately constant along the whole intensity range. This forms a basis f
 or statistical inference from microarray data\, and provides a rational da
 ta pre-processing strategy for multivariate analyses. For the transformati
 on h\, the parametric form h(x)=arsinh(a+bx) is derived from a model of th
 e variance-versus-mean dependence for microarray intensity data\, using th
 e method of variance stabilizing transformations. For large intensities\, 
 h coincides with the logarithmic transformation\, and Deltah with the log-
 ratio. The parameters of h together with those of the calibration between 
 experiments are estimated with a robust variant of maximum-likelihood esti
 mation. We demonstrate our approach on data sets from different experiment
 al platforms\, including two-colour cDNA arrays and a series of Affymetrix
  oligonucleotide arrays.\n\nAnyone is welcome to attend.\n\n\n\n
LOCATION:Lecture Room\,  Sanger Building\,  Biochemistry Department
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