What Is Apdex?

Apdex is an open standard developed by the Apdex alliance. It defines a standard method to measure application performance. The Apdex standard converts the application response time into user satisfaction with application performance in the range of 0 to 1.

• Apdex principle

  Apdex defines the threshold "T" for application response time. "T" is determined based on performance expectations. Based on the actual response time and "T", user experience can be categorized as follows:

  Satisfied: indicates that the actual response time is shorter than or equal to "T". For example, if "T" is 1.5s and the actual response time is 1s, user experience is satisfied.

  Tolerable: indicates that the actual response time is greater than "T", but shorter than or equal to "4T". For example, if "T" is 1s, the tolerable upper threshold for the response time is 4s.

  Frustrated: indicates that the actual response time is greater than "4T".

  

• Apdex calculation

  In APM, the Apdex threshold is the maximum response time that makes users satisfied. The application response latency is the service latency. The Apdex value ranges from 0 to 1 and is calculated as follows:

  Apdex = (Number of satisfied samples + Number of tolerable samples × 0.5)/Total number of samples