Lower bound of Wilson score confidence interval for a Bernoulli parameter: https://www.evanmiller.org/how-not-to-sort-by-average-rating.html

wilson.go

package main

import (
	"fmt"
	"math"

	"gonum.org/v1/gonum/stat/distuv"
)

func main() {
	// Use fixed value (quantile(95%) = 1.6448536269514715),
	// if calculating normal distribution or importing gonum is too expensive for you.
	z := distuv.UnitNormal.Quantile(0.95)
	fmt.Println(z)

	fmt.Println(score(600, 1000, z))
	fmt.Println(score(5500, 10000, z))
}

// score returns a lower bound of Wilson score, best use when scoring/ranking.
// Make sure to read this first: https://www.evanmiller.org/how-not-to-sort-by-average-rating.html
//
// positive: Number of positive votes.
// total: Total number of votes.
// z: Inverse of the Gauss's normal distribution.
func score(positive, total, z float64) float64 {
	if total == 0 {
		return 0
	}

	phat := positive/total
	return (phat + z*z/(2*total) - z * math.Sqrt((phat*(1-phat)+z*z/(4*total))/total))/(1+z*z/total)
}