netdata/web/api/queries/trimmed_mean

Trimmed Mean

The trimmed mean is the average value of a series excluding the smallest and biggest points.

Netdata applies linear interpolation on the last point, if the percentage requested to be excluded does not give a round number of points.

The following percentile aliases are defined:

• trimmed-mean1
• trimmed-mean2
• trimmed-mean3
• trimmed-mean5
• trimmed-mean10
• trimmed-mean15
• trimmed-mean20
• trimmed-mean25

The default trimmed-mean is an alias for trimmed-mean5. Any percentage may be requested using the group_options query parameter.

how to use

Use it in alarms like this:

 alarm: my_alarm
    on: my_chart
lookup: trimmed-mean5 -1m unaligned of my_dimension
  warn: $this > 1000

trimmed-mean does not change the units. For example, if the chart units is requests/sec, the result will be again expressed in the same units.

It can also be used in APIs and badges as &group=trimmed-mean in the URL and the additional parameter group_options may be used to request any percentage (e.g. &group=trimmed-mean&group_options=29).

Examples

Examining last 1 minute successful web server responses:

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References

• https://en.wikipedia.org/wiki/Truncated_mean.