tl;dr: Don't bother with confidence intervals. Use a G-test instead. Calculate it here: http://elem.com/~btilly/effective-ab-testing/g-test-calculator.html htt

tl;dr: Don't bother with confidence intervals. Use a G-test instead. Calculate it here: http://elem.com/~btilly/effective-ab-testing/g-test-calculator.html http://elem.com/~btilly/effective-ab-testing/g-test-calculat... Read more here: http://en.wikipedia.org/wiki/G-test http://en.wikipedia.org/wiki/G-test And plain English here: http://en.wikipedia.org/wiki/Likelihood_ratio_test http://en.wikipedia.org/wiki/Likelihood_ratio_test