Try out http://www.evanmiller.org/ab-testing/chi-squared.html http://www.evanmiller.org/ab-testing/chi-squared.html. That's what we use at SimplePrints all the

Try out http://www.evanmiller.org/ab-testing/chi-squared.html http://www.evanmiller.org/ab-testing/chi-squared.html. That's what we use at SimplePrints all the time. Great library of functions.