    def dimension_reduce(results)
      # calculate the weighted Euclidean distance from optimal
      # d(p, q) = \sqrt{(p_1 - q_1)^2 + (p_2 - q_2)^2+...+(p_n - q_n)^2}
      # here the max value is sqrt(n) where n is no. of results,
      #   min value (optimum) is 0
      total = 0
      results.each_value do |value|
        o = value[:optimum]
        w = value[:weighting]
        a = value[:result]
        m = value[:max]
        total += w * (((o - a) / m)**2) if m != 0
      end
      Math.sqrt(total) / results.length
    end