The Apdex Users Group community is constantly improving how to apply the methodology. The approach has also evolved into covering much more than application response time. Below are some useful references.

We welcome additional papers on how the methodology was used for any dataset of measurements. Apdex is no longer limited to application performance.

Original Formal Specifications

Application Performance Index (Apdex) Technical Specification V1.1
January 22, 2007

Application Performance Index (Apdex) Technical Specification V1.0
September 22, 2005

Valuable Reference Material

How to Choose Apdex T
By New Relic

Defining Apdex
Early Article by Peter Sevcik

Integrating Apdex with Barry-3
By Performance Dynamics Company

Easily measure and manage user experience with more flexible Apdex calculations
By Dynatrace

Using histograms to approximate Apdex scores
By Splunk

See side-by-side test results of ten web sites from five US user locations that are reported using averages and Apdex.  The results are documented in “Averages Hide the Real End-User Experience: Apdex Tells the Full Story,” NFR 5086 by Peter Sevcik, April 2007.  The Apdex reports of the very same measurement data uncover many more performance issues.

Read a Tolly Group white paper on Guaranteed WAN Application Performance Using Ipanema Technologies products (December 2006). The White Paper evaluates the Ipanema System Ver. 4.3 and illustrates its effectiveness in providing desirable and predictable application performance in congested networks.  The results are shown using the Apdex methodology.