• http://twitter.com/bennyblum Benny Blum

    Quick follow up: this same test can be used to determine the effectiveness of an A/B test. Rather than setting the control to 0 sign ups and 100 visitors, just enter your actual conversion rate (ex: 8 sign ups and 1352 visits) and then the data for the test in progress (ex: 13 sign ups and 1191 visits). The calculator will tell you if the variance is statistically significant.

  • http://twitter.com/DelvePartners Delve Partners

    When dealing with uneven proportions, statistical power can be very elusive and lead to inaccurate T, Z or Chisquare results.

    Good writeup.

    Jeff