Reddit Ranking Algorithm in JavaScript

ranking.js

function _confidence(ups, downs) {
	var n = ups + downs;

	if(n === 0) {
		return 0;
	}

	var z = 1.281551565545;
	var p = parseFloat(ups) / n;
	var left = p + 1 / (2 * n) * z * z;
	var right = z * Math.sqrt(p * (1 - p) / n + z * z / (4 * n * n));
	var under = 1 + 1 / n * z * z;

	return (left - right) / under;
}

function confidence(ups, downs) {
	if(ups + downs === 0) {
		return 0;
	} else {
		return _confidence(ups, downs);
	}
}

Hey! tks for sharing
I am quite new, but couldn't find Date as parameter. doesn't it affect the results?