sscore (version 1.44.0)

SScore: Compute S-Score values

Description

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

Usage

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)

Arguments

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

Value

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

Details

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.

References

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

See Also

SScoreBatch,computeSFandSDT,computeOutlier

Examples

  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)

}