Application Performance Index, this is a numerical measure of user satisfaction, it is based on three zones of application responsiveness:
- Satisfied: The user is fully productive. This represents the time value (T seconds) below which users are not impeded by application response time.
- Tolerating: The user notices performance lagging within responses greater than T, but continues the process.
- Frustrated: Performance with a response time greater than 4*T seconds is unacceptable, and users may abandon the process.
By default T is set to 1.5s this means that response time between 0 and 1.5s the user is fully productive, between 1.5 and 6s the responsivness is tolerating and above 6s the user is frustrated.
The Apdex score converts many measurements into one number on a uniform scale of 0-to-1 (0 = no users satisfied, 1 = all users satisfied).
To ease interpretation the Apdex score is also represented as a rating:
- U for UNACCEPTABLE represented in gray for a score between 0 and 0.5
- P for POOR represented in red for a score between 0.5 and 0.7
- F for FAIR represented in yellow for a score between 0.7 and 0.85
- G for Good represented in green for a score between 0.85 and 0.94
- E for Excellent represented in blue for a score between 0.94 and 1
Visit http://www.apdex.org/ for more information.