Perl scoring module that uses statistics standard score

 Statistics::Zscore is a scoring module that uses statistics STANDARD SCORE.
 .
 In statistics, a standard score is a dimensionless quantity
 derived by subtracting the population mean from an individual raw score
 and then dividing the difference by the population standard deviation.
 .
 This conversion process is called standardizing or normalizing.
 Standard scores are also called z-values, z-scores, normal scores,
 and standardized variables.
 .
 See http://en.wikipedia.org/wiki/Standard_score for more information.