In order for this second test to be valid at 95 australia business email lists % confidence, 15 out of the 20 tests will need to show that nofollow was an effective PageRank sculpting method. If this doesn't happen, we will need to run a third test with a much bigger sample size. If we want to be 95% sure we will detect nofollow being better with 95% significance even if the odds nofollow wins a given trial is only 5 out of 8, we will need 168 test pairs.
(See math below) What keeps you from making the same mistake? While reworking the old test, I got the help of Ben Hendrickson who sits a few desks away. Please feel free to check our math before we run the test. The Math Behind the 168 Pairs Nofollow Test This test consists of a number of independent trials. In each trial, either nofollow or the control will rank higher. Thus the number of wins will be distributed according to a binomial distribution.