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This adds docs for all of ESQL's aggregation functions. Hopefully from here on out we can add the docs as we add new functions. I've created a few tagged regions in the aggs docs themselves so we can include them into the ESQL docs. --------- Co-authored-by: Abdon Pijpelink <abdon.pijpelink@elastic.co>
28 lines
1.1 KiB
Text
28 lines
1.1 KiB
Text
[[esql-agg-median-absolute-deviation]]
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=== `MEDIAN_ABSOLUTE_DEVIATION`
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The median absolute deviation, a measure of variability. It is a robust
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statistic, meaning that it is useful for describing data that may have outliers,
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or may not be normally distributed. For such data it can be more descriptive than
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standard deviation.
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It is calculated as the median of each data point’s deviation from the median of
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the entire sample. That is, for a random variable `X`, the median absolute deviation
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is `median(|median(X) - Xi|)`.
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[source.merge.styled,esql]
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----
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include::{esql-specs}/stats_percentile.csv-spec[tag=median-absolute-deviation]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/stats_percentile.csv-spec[tag=median-absolute-deviation-result]
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|===
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NOTE: Like <<esql-agg-percentile>>, `MEDIAN_ABSOLUTE_DEVIATION` is
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<<esql-agg-percentile-approximate,usually approximate>>.
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[WARNING]
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====
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`MEDIAN_ABSOLUTE_DEVIATION` is also {wikipedia}/Nondeterministic_algorithm[non-deterministic].
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This means you can get slightly different results using the same data.
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====
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