Standard Deviation is an important metric in performance testing analysis and informs us how stable the application under test is. In other words, it tells us if the requests that occur during the test are consistent or not.
Standard Deviation measures how the response times are spread out around the average response time (mean).
A small standard deviation means that the response time of all the requests are close to each other. Which leads us to understand that a smaller standard deviation value the closer the response times are and more consistent the transaction is, and stable the application tested.
It’s not very easy to calculate the standard deviation, especially for large datasets, that’s why most of the tools calculate it for you and show a summary for a better understanding on how the application behaves in the real world.
When you run a performance test with LoadFocus, either that you test a website, a REST API or you run a JMeter load test, the Standard Deviation is calculated automatically, and it’s visible in the Load Test result, under the Insights tab. See here more details about Standard Deviation and percentiles.
Written by Bogdan Vazzolla.
LoadFocus is a cloud performance, load and stress testing tool which provides the infrastructure to run tests with thousands of concurrent users, from multiple cloud locations, in less than a few minutes, keep history of the results, compare different runs to inspect performance improvements or performance degradation. It also supports running JMeter load tests from the cloud.