dacohen/Rsquared

module Rsquared
##
  # Tests for outliers on either side of the data
  # grubbs = Rsquared::GrubbsTest.new(data)
  # grubbs.significant? => Boolean
  #

  class GrubbsTest
      ##
      # Initializes the Test object with an array of numerical data
      #

      def initialize(data)
         @data = data.sort
            @gstat = [((@data.mean - @data.min)/@data.stddev).abs, ((@data.mean - @data.max)/@data.stddev).abs].max
      end
      
      ##
      # Returns a boolean indicating the significance of the test at the 5% level
      #      

      def significant?(alpha=0.05)
         if @gstat > Helper::grubbscv(@data.length, alpha) then
             return true
         else
        return false
         end
      end

      def inspect
          significant?
      end

      ##
      # Returns the test statistic as a float
      #

      def statistic
          @gstat
      end

      alias_method :outlier?, :significant?          
  end
end