In statistics, multivariate testing or multi-variable testing is a technique for testing hypotheses on complex multi-variable systems, especially used in testing market perceptions.^[1]

[edit] In internet marketing

In internet marketing, multivariate testing is a process by which more than one component of a website may be tested in a live environment. It can be thought of in simple terms as numerous split tests or A/B tests performed on one page at the same time. Split tests and A/B tests are usually performed to determine the better of two content variations, multivariate testing can theoretically test the effectiveness of limitless combinations. The only limits on the number of combinations and the number of variables in a multivariate test are the amount of time it will take to get a statistically valid sample of visitors and computational power.

Multivariate testing is usually employed in order to ascertain which content or creative variation produces the best improvement in the defined goals of a website, whether that be user registrations or successful completion of a checkout process (ie conversion rate). Dramatic increases can be seen through testing different copy text, form layouts and even landing page images and background colours.

Testing can be carried out on a dynamically generated website by setting up the server to display the different variations of content in equal proportions to incoming visitors. Statistics on how each visitor went on to behave after seeing the content under test must then be gathered and presented. Outsourced services can also be used to provide multivariate testing on websites with minor changes to page coding. These services insert their content to predefined areas of a site and monitor user behavior.

In a nutshell, multivariate testing can be seen as allowing website visitors to vote with their clicks for which content they prefer and will stand the most chance of them proceeding to a defined goal. The testing is transparent to the visitor with all commercial solutions capable of ensuring that each visitor is shown the same content as they first saw on each subsequent visit.

Some websites benefit from constant 24/7 continuous optimisation as visitor response to creatives and layouts differ by time of day/week or even season.

Multivariate testing is currently an area of high growth in internet marketing as it helps website owners to ensure that they are getting the most from the visitors arriving at their site. Areas such as SEO and pay per click advertising bring visitors to a site and have been extensively used by many organisations but multivariate testing allows internet marketeers to ensure that visitors are being effectively exploited once they arrive at the website.

[edit] Designs of experiment

Statistical testing relies on design of experiments. Several methods in use for multivariate testing include:

1. Experimental design involves iterations and waves of testings.
2. Taguchi methods: with multiple variations of content in multiple locations on a website, a large number of combinations need to be statistically tested and medium/low traffic websites can take some time to get a large enough sample of visitors to decide which content gives the best performance. For example, if 3 different images are to be tested in 3 locations, there are 27 combinations to test. Taguchi methods (namely Taguchi orthogonal arrays) can be used in the design of experiments in order to reduce the variations but still give statistically valid results on individual content elements.