Total-experience testing, or experience testing, is a type of experiment-based testing in which the entire website experience of the visitor is examined using technical capabilities of the website platform (e.g., ATG, Blue Martini Software, etc.). Rather than creating multiple websites, total-experience testing uses the website platform to create several persistent experiences, and monitors which one is preferred by the customers.
The metaphor of the funnel is used because people drop away at each stage of a long sales process: for example, many of your unqualified prospects may have existing suppliers with whom they're very satisfied. Others may have needs which other competitors are better-placed to satisfy. Still, others may love your products, but not have the budget to buy them.