A/B Tests in Marketing – Sample Size and Significance using R

Hypothesis Test: Difference Between Proportions

http://stattrek.com/hypothesis-test/difference-in-proportions.aspx

G-test vs T-test, which is better for A/B testing?

http://stats.stackexchange.com/questions/25209/difference-between-g-test-and-t-test-and-which-should-be-used-for-a-b-testing

Awell-known A/B test tutorial:

http://elem.com/~btilly/effective-ab-testing/

How do you determine what is “statistically significant” when looking at the results of an A/B test?

http://www.quora.com/How-do-you-determine-what-is-statistically-significant-when-looking-at-the-results-of-an-A-B-test

For better understanding, one should take course in statistical inference:

https://www.edx.org/course/uc-berkeleyx/uc-berkeleyx-stat2-3x-introduction-1533#.VEVFCSSfiaB