SScore: Compute S-Score values
In sscore: S-Score Algorithm for Affymetrix Oligonucleotide Microarrays

Description Usage Arguments Details Value Note Author(s) References See Also Examples

View source: R/SScore.R

Computes the S-Score values for a pair of Affymetrix GeneChips

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SScore(afbatch = stop("No CEL files specified"), classlabel = c(0,1), SF = NULL, 
       SDT = NULL, rm.outliers = TRUE, rm.mask = TRUE, rm.extra = NULL, 
       digits = NULL, verbose = FALSE, celfile.path = NULL, celfile.names = NULL)

`afbatch`	An `AffyBatch` object
`classlabel`	A vector identifying the class for each column of the `AffyBatch` object
`SF`	a list of Scale Factor (SF) values for each GeneChip
`SDT`	a list of Standard Difference Threshold (SDT) values for each GeneChip
`rm.outliers`	should the spots marked as 'OUTLIERS' be excluded from S-Score calculation?
`rm.mask`	should the spots marked as 'MASKS' be excluded from S-Score calculation?
`rm.extra`	if `TRUE`, overrides what is in `rm.mask` and `rm.outliers`
`digits`	number of significant digits for S-Score values
`verbose`	logical value. If `TRUE` it provides more detail of the S-Score calculations.
`celfile.path`	character denoting the path for the *.CEL files corresponding to `afbatch`
`celfile.names`	optional character vector containing the names of the *.CEL files

Computes S-Score values as described by Zhang et al. (2002). SScore provides a simpler interface for comparing only two classes of GeneChips, while SScoreBatch compares multiple pairs of chips.

The classlabel consists of a vector with one entry for each column of the AffyBatch object. Each entry consists of a 0 or a 1 to identify the class to which the chip for the corresponding column belongs. SScore will conduct a two-class test comparing all chips labeled 0 to all chips labeled 1. If classlabel is not specified, it defaults to a two-chip comparison, compatible with previous versions of SScore.

The SF and SDT factors are required for all calculations. If NULL, these values will be calculated according to the Affymetrix Statistical Algorithms Description Document. digits allows the specification of the number of significant digits for the S-Score values; if NULL, the maximum number of significant digits are retained.

An ExpressionSet with S-Score values in the exprs slot.

Based on C++ code by Li Zhang and Delphi code by Robnet Kerns

Richard Kennedy rkennedy@vcu.edu

Zhang, L., Wang, L., Ravindranathan, A., Miles, M.F. (2002) A new algorithm for analysis of oligonucleotide arrays: application to expression profiling in mouse brain regions. Journal of Molecular Biology, 317(2), pp. 225–35

Kerns, R.T., Zhang, L., Miles, M.F. (2003) Application of the S-score algorithm for analysis of oligonucleotide microarrays. Methods, 31(4), pp. 274–81

SScoreBatch,computeSFandSDT,computeOutlier

  if (length(dir(pattern=".cel$")) != 0) {

  ## Read in the *.CEL files
  abatch <- ReadAffy()

  ## default calling method
  SScores <- SScore(abatch)

  ## specifying SF and SDT (gives same results as above)
  SfSdt <- computeSFandSDT(abatch)
  SScores <- SScore(abatch,SF=SfSdt$SF,SDT=SfSdt$SDT)

  ## specifying outlier and masked values should be included in calculations
  SScores <- SScore(abatch,rm.outliers=FALSE,rm.mask=FALSE)

  ## round results to 3 significant digits
  SScores <- SScore(abatch,digits=3)

  ## show verbose output
  SScores <- SScore(abatch,verbose=TRUE)

}