sample_variance - Calculate the variance of an expression
The sample_variance
command computes the variance of a given value. This is especially useful for answering the question "Is this value normal?".
NOTE: sample_variance
is used when we only have a subset of data. For example, if we have heavy sampling on traces, we may wish to use the sample_variance
rather than global variance, to be more statistically accurate.
Syntax
Arguments
Name | Type | Required | Description |
---|---|---|---|
expression | number | true | The expression for which we will find the sample variance |
Example - Computing variance of duration in Traces
We can calculate the variance of the duration
metadata field for a collection of traces, and group the results by operationName
in the following way:
This will let us know how much the duration of a given operationName
varies over the specified timerange, when we don't have a complete dataset.
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