Apdex is a standard to measure the users' satisfaction and experience on using your applications. The faster the response time, the higher the apdex score.
Apdex is a measure of response time based against a set threshold. You have to define a response time threshold T in Project settings.
For example, if T is 3 seconds and a response completes in 2.5 seconds, then the user is satisfied. All responses greater than 3 seconds dissatisfy the user.
Apdex tracks three response counts:
- Satisfied: The response time is less than or equal to T.
- Tolerated: The response time is greater than T and less than or equal to 4T.
- Frustrated: The response time is greater than 4T, the users might abandon the web site or app.
Formula to calculate Apdex
The Apdex formula is the number of satisfied samples plus half of the tolerating samples divided by all the samples. Samples from frustrated users do not count.
Apdex Score = ((Satisfied user requests) + (Tolerable user requests/2))/Total number of user requests
Threshold value = 2 seconds
Total number of requests = 500
Number of satisfied user = 200 (response time <= 2 seconds)
Number of tolerable user = 100 (response time = 2-8 seconds)
Number of frustrated user = 200 (response time > 8 seconds)
Apdex score will be 0.5