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Rating models

Wilson lower bound calculator

Calculate a conservative ranking score from positive and negative review counts.

Model estimate, not a platform prediction. Results may differ from real service ratings. Platforms can use unpublished weights, moderation, eligibility rules and rounding. This calculator applies only the formula below.

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Wilson lower bound · model result
82.563%

90 positive out of 100 reviews. Observed positive rate: 90.00%.

Results are rounded to three decimal places.

How it works

(p + z²/(2n) − z × √(p(1−p)/n + z²/(4n²))) ÷ (1 + z²/n)

Uses z = 1.959963984540054, the lower endpoint of a two-sided 95% Wilson confidence interval. This is a ranking statistic, not a star average or a guarantee about the true positive rate. It assumes independent binary observations.

NIST: confidence intervals for proportions

Results update as you type. Calculations run in your browser; submitting with JavaScript disabled sends the numbers to the server to calculate the result.

Reach a target

Minimum additional positive reviews. Existing negative reviews stay unchanged. Target refers to this method’s score, not a displayed star rating.

263

additional reviews needed

Simulate new ratings

84.070%

100 positive out of 110 reviews. Observed positive rate: 90.91%.

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