 location
 color
 button type
 surrounding type
 text font
 font size
 any graphic you use
 product descriptions
 sales copy
 verbiage
 different offers (50% off, 35% off, free sample, etc.)
 a whole page
 a whole landing page
Then you set your control element/variable, and it is essentially what you have now, and you call that your A. Meanwhile, the element/variable you want to test as B, to be run simultaneously with the control (Christian, 2012; Patel, n.d.). The A and B variables are also known as variants, the challenger is the B variable, and the champion variable is the one that outperforms the others (unbounce.com, n.d.) For instance, 100% of the audience will be split into 50% of your site with variable A and the other 50% of your site with variable B. The split can vary from 50/50 to 60/40 to 70/30, etc. and it depends on how much weight you want to assign to the challenger variable (unbounce.com, n.d).
 If Gaussian is the assumed distribution (i.e. average revenue per paying user), you can use the Unpaired Ttest and/or Student Ttest (Amazon, 2015; Box et al., 1987; Pereira, 2007).
 If Binomial is the assumed distribution (i.e.click through rate), you can use Fisher’s exact test and/or Bernard’s test (Amazon, 2015).
 If Poisson is the assumed distribution (i.e. transactions per paying user), you can use the Etest and/or Ctest (Krishnamoorthy & Thomson, 2004).
 If Multinomial is the assumed distribution (i.e. the number of each product purchased), you can use the Chisquare test.
 If the assumed distribution is unknown, you can use the MannWhitney U test and/or Gibbs Sampling.

Box, Joan Fisher. Guinness, Gosset, Fisher, and Small Samples. Statist. Sci. 2 (1987), no. 1, 45–52. doi:10.1214/ss/1177013437. https://projecteuclid.org/euclid.ss/1177013437

Christian, B. (2012) The A/B test: inside the technology that’s changing the rules of business. Retrieved from https://www.wired.com/2012/04/ffabtesting
 Amazon.com (2015). The math behind A/B Testing. Retrieved from https://web.archive.org/web/20150921174256/https://developer.amazon.com/public/apis/manage/abtesting/doc/mathbehindabtesting
 Kolowich, L. (n.d). How to do A/B testing: A checklist you’ll want to bookmark. Retrieved from https://blog.hubspot.com/marketing/howtodoabtesting
 Krishnamoorthy, K. and Thomson, J. (2004). A more powerful test of comparing two Poisson means. Journal of Statistical Planning and inference. 119(1), 2335. Retrieved from https://doi.org/10.1016/S03783758(02)004081
 Patel, N. (n.d.). A Beginner’s Guide to A/B Testing: An introduction. Retrieved from https://neilpatel.com/blog/abtestingintroduction/
 Pereira, R. (2007). How beer influenced statistics. Retrieved from https://blog.gembaacademy.com/2007/06/20/howbeerinfluencedstatistics/
 Unbounce.com (n.d.). What is A/B testing? Retrieved from https://unbounce.com/landingpagearticles/whatisabtesting/