Class: TrailGuide::Calculators::Score
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
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
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.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
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.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
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.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
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.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
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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 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
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