What Are the Apdex and Apdex Threshold?

Apdex Principles

An Apdex threshold is the optimal threshold for the application response time. Based on the Apdex threshold and actual application response time, there are the following three kinds of performance:

Satisfied: The actual application response time is less than or equal to the Apdex threshold. For example, if the Apdex threshold is 1.5s and the response time is 1s, the result is satisfied.

Tolerable: The actual application response time is greater than the Apdex threshold, but less than or equal to 4 times of the Apdex threshold. For example, if the Apdex threshold is 1s, the tolerable upper threshold for the application response time is 4s (4 x 1s).

Frustrated: The application response time is greater than 4 times of the Apdex threshold.

Apdex Calculation Method

In Application Performance Management (APM), the Apdex threshold is the threshold configured according to Setting Apdex Thresholds, and the application response latency is the service latency. The Apdex value ranges from 0 to 1 and is calculated as follows:

Apdex = (Satisfied samples x 1 + Tolerable samples x 0.5 + Frustrated samples x 0)/Total number of samples

Apdex calculation results indicate application performance status, that is, user satisfaction with application performance. Different colors indicate different Apdex ranges. For details, see Table 1.

Example

As shown in the preceding figure, the number of satisfied calls is 50, the number of tolerable calls is 0, the number of frustrated calls is 30, and the number of error calls is 0. There are 80 calls in total.

According to the formula:

Apdex = (Satisfied samples x 1 + Tolerable samples x 0.5 + Frustrated samples x 0)/Total number of samples

Apdex = (50 x 1 + 0 x 0.5 + 30 x 0)/80 = 0.63

Configuring an Apdex Threshold

You can configure the Apdex threshold as required. For details, see Setting Apdex Thresholds.