I would actually go by jwj's rather simple explanation of this thingie bob......after reading this
"The Apdex Alliance is a group of companies collaborating to promote an application performance metric called Apdex. Apdex is a numerical measure of user satisfaction with the performance of enterprise applications, and reflects the effectiveness of IT investments in contributing to business objectives...."
looks like another numeric study of something that cannot be readily quantized.
Picking pebbles on the shore of the networking ocean