Module: CompletionKit::CalibrationMath

Defined in:
app/services/completion_kit/calibration_math.rb

Constant Summary collapse

Z_95 = 
1.959963984540054

Class Method Summary collapse

Class Method Details

.mae(pairs) ⇒ Object 



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# File 'app/services/completion_kit/calibration_math.rb', line 18

def mae(pairs)
  return nil if pairs.empty?
  sum = pairs.sum { |ai, human| (ai.to_f - human.to_f).abs }
  sum / pairs.length
end

.pearson(pairs) ⇒ Object 



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# File 'app/services/completion_kit/calibration_math.rb', line 24

def pearson(pairs)
  return nil if pairs.length < 2
  xs = pairs.map { |a, _| a.to_f }
  ys = pairs.map { |_, h| h.to_f }
  mx = xs.sum / xs.length
  my = ys.sum / ys.length
  num = xs.zip(ys).sum { |x, y| (x - mx) * (y - my) }
  dx2 = xs.sum { |x| (x - mx)**2 }
  dy2 = ys.sum { |y| (y - my)**2 }
  denom = Math.sqrt(dx2 * dy2)
  return nil if denom.zero?
  num / denom
end

.quadratic_weighted_kappa(pairs, categories:) ⇒ Object 



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# File 'app/services/completion_kit/calibration_math.rb', line 38

def quadratic_weighted_kappa(pairs, categories:)
  return nil if pairs.empty?

  ratings = categories.to_a
  k = ratings.length
  return nil if k < 2

  index = ratings.each_with_index.to_h
  observed = Array.new(k) { Array.new(k, 0) }
  row_totals = Array.new(k, 0)
  col_totals = Array.new(k, 0)
  n = 0

  pairs.each do |ai, human|
    i = index[score_bucket(ai, ratings)]
    j = index[score_bucket(human, ratings)]
    next if i.nil? || j.nil?
    observed[i][j] += 1
    row_totals[i] += 1
    col_totals[j] += 1
    n += 1
  end
  return nil if n.zero?

  max_dist_sq = (k - 1.0)**2
  numerator = 0.0
  denominator = 0.0
  (0...k).each do |i|
    (0...k).each do |j|
      weight = ((i - j)**2) / max_dist_sq
      expected = (row_totals[i] * col_totals[j]).to_f / n
      numerator   += weight * observed[i][j]
      denominator += weight * expected
    end
  end
  return 1.0 if denominator.zero?
  1.0 - (numerator / denominator)
end

.score_bucket(value, ratings) ⇒ Object 



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# File 'app/services/completion_kit/calibration_math.rb', line 77

def score_bucket(value, ratings)
  rounded = value.to_f.round
  return ratings.first if rounded <= ratings.first
  return ratings.last if rounded >= ratings.last
  rounded
end

.wilson_interval(successes:, n:, z: Z_95) ⇒ Object 



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# File 'app/services/completion_kit/calibration_math.rb', line 7

def wilson_interval(successes:, n:, z: Z_95)
  return { point: nil, low: nil, high: nil } if n.to_i.zero?

  p_hat = successes.to_f / n
  denom = 1.0 + (z * z) / n
  center = (p_hat + (z * z) / (2.0 * n)) / denom
  margin = z * Math.sqrt((p_hat * (1 - p_hat) / n) + ((z * z) / (4.0 * n * n))) / denom

  { point: p_hat, low: [center - margin, 0.0].max, high: [center + margin, 1.0].min }
end