Standard Deviation Value is used in reports to provide greater depth of analysis.
STDDev (STDDev is an acronym of Standard Deviation) shows how much variation there is from the “average” (mean). A low standard deviation indicates that the data points tend to be very close to the mean, whereas a high standard deviation indicates that the data are spread out over a large range of values.
In other words, a higher value shows that something is causing response times to jump around and this indicates unstable service performance.
Dotcom-Monitor utilized the following formula for calculation
Standard Deviation Value
x – Duration
n – response quantity