Class: TrailGuide::Calculators::Score

Inherits:
Calculator
  • Object
show all
Defined in:
lib/trail_guide/calculators/score.rb

Instance Attribute Summary

Attributes inherited from Calculator

#choice, #experiment, #goal, #probability

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Calculator

#base, #best, #initialize, #variants, #variants_with_conversion, #worst

Constructor Details

This class inherits a constructor from TrailGuide::Calculators::Calculator

Class Method Details

.all_probabilities ⇒ Object 



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# File 'lib/trail_guide/calculators/score.rb', line 14

def self.all_probabilities
  @@all_probabilities ||= (0.0..100.0).step(0.1).map { |pct| [z_score_probabilities.find { |x,a| a >= pct }.first, pct] }.reverse
end

.significant_probabilities ⇒ Object 



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# File 'lib/trail_guide/calculators/score.rb', line 18

def self.significant_probabilities
  @@significant_probabilities ||= TrailGuide::Calculators::SIGNIFICANT_PROBABILITIES.map { |pct| [z_score_probabilities.find { |x,a| a >= pct }.first, pct] }.reverse
end

.significant_probability(score) ⇒ Object 



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# File 'lib/trail_guide/calculators/score.rb', line 28

def self.significant_probability(score)
  score = score.abs
  probability = significant_probabilities.find { |z,p| score >= z }
  probability ? probability.last : 0
end

.z_score_probabilities ⇒ Object

array of [z-score, percentage]



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# File 'lib/trail_guide/calculators/score.rb', line 5

def self.z_score_probabilities
  @@z_score_probabilities ||= begin
    avg = 50.0
    norm_dist = []
    (0.0..3.1).step(0.01) { |x| norm_dist << [x, avg += 1 / Math.sqrt(2 * Math::PI) * Math::E ** (-x ** 2 / 2)] }
    norm_dist
  end
end

.z_score_probability(score) ⇒ Object 



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# File 'lib/trail_guide/calculators/score.rb', line 22

def self.z_score_probability(score)
  score = score.abs
  probability = all_probabilities.find { |z,p| score >= z }
  probability ? probability.last : 0
end

Instance Method Details

#calculate! ⇒ Object 



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# File 'lib/trail_guide/calculators/score.rb', line 34

def calculate!
  pc = base.measure
  nc = base.superset
  variants_with_conversion.each do |var|
    p = var.measure
    n = var.superset
    z_score = (p - pc) / ((p * (1-p)/n) + (pc * (1-pc)/nc)).abs ** 0.5

    var.z_score = z_score
    var.probability = self.class.z_score_probability(z_score)
    var.probability = -(var.probability) if var.z_score.negative?
    var.significance = self.class.significant_probability(z_score)
    var.significance = -(var.significance) if var.z_score.negative?

    #if worst && var.measure > worst.measure
    #  var.difference = (var.measure - worst.measure) / worst.measure * 100
    #end
    if base
      if var.measure > base.measure
        var.difference = (var.measure - base.measure) / base.measure * 100
      elsif base.measure > var.measure
        var.difference = -((base.measure - var.measure) / base.measure * 100)
      else
        var.difference = 0
      end
    end
  end

  @choice = best && best.probability >= probability ? best : nil

  self
end