Multivariate Testing: A type of testing that varies and tests more than one or two campaign elements at a time to determine the best performing elements and combinations. Multivariate testing can gather significant results on many different components of, for example, alternative PPC ad titles or descriptions in a short period of time. Often it requires special expertise to analyze complex statistical results. (Compare to A/B Testing which changes only one element at a time, alternately serving an “old” version ad and a changed ad.) In search advertising, you might do A/B Split or Multivariate testing to learn what parts of a landing page (background color, title, headline, fill in forms, design, images) produce higher conversions and are more cost effective.