Behaviorism
The book, Understanding User - Web Interactions Via Web Analytics, discusses behaviorism as the theoretical basis for Web Analytics.
A lot of folks have really 'dissed' behaviorism, with some validity. However, if you look at the range of research methods on the quantitative side, the behaviorist won the discussion. Here is a interesting article discussing the early years of behaviorism, including the behaviorist manifesto, Behaviourism: The Early Years