Don't sort by average ratings

gistfile1.txt

http://www.evanmiller.org/how-not-to-sort-by-average-rating.html






sub ci_lower_bound ( $postive_ratings, $total_ratings, $confidence = 0.95 ) {
	return 0 if $total_ratings == 0;
	
	my $z = 1.96;
	
	my $p_hat = $postive_ratings / $total_ratings;
	
	( $phat + $z**2/(2*$total_ratings) 
	- z * 
	sqrt( ( $phat*(1-$phat) + (z**2/(4*$total_ratings)) ) / $total_ratings ) 
		/ 
	(1 + z**2/$total_ratings)


    (
    	phat + z*z/(2*n) - z * Math.sqrt(
    		( phat*(1-phat)+z*z/(4*n) ) / n
    		)
    	
    )/(1+z*z/n)





__END__
require 'statistics2'

def ci_lower_bound(pos, n, confidence)
    if n == 0
        return 0
    end
    z = Statistics2.pnormaldist(1-(1-confidence)/2)
    phat = 1.0*pos/n
    (phat + z*z/(2*n) - z * Math.sqrt((phat*(1-phat)+z*z/(4*n))/n))/(1+z*z/n)
end