elasticsearch/docs/reference/query-languages/esql/_snippets/functions/median_absolute_deviation.md

MEDIAN_ABSOLUTE_DEVIATION [esql-median_absolute_deviation]

Syntax

:::{image} ../../../../../images/median_absolute_deviation.svg :alt: Embedded :class: text-center :::

Parameters

true Description

Returns the median absolute deviation, a measure of variability. It is a robust statistic, meaning that it is useful for describing data that may have outliers, or may not be normally distributed. For such data it can be more descriptive than standard deviation. It is calculated as the median of each data point’s deviation from the median of the entire sample. That is, for a random variable X, the median absolute deviation is median(|median(X) - X|).

::::{note} Like PERCENTILE, MEDIAN_ABSOLUTE_DEVIATION is usually approximate. ::::

Supported types

number	result
double	double
integer	double
long	double

Examples

FROM employees
| STATS MEDIAN(salary), MEDIAN_ABSOLUTE_DEVIATION(salary)

MEDIAN(salary):double	MEDIAN_ABSOLUTE_DEVIATION(salary):double
47003	10096.5

The expression can use inline functions. For example, to calculate the median absolute deviation of the maximum values of a multivalued column, first use MV_MAX to get the maximum value per row, and use the result with the MEDIAN_ABSOLUTE_DEVIATION function

FROM employees
| STATS m_a_d_max_salary_change = MEDIAN_ABSOLUTE_DEVIATION(MV_MAX(salary_change))

m_a_d_max_salary_change:double
5.69

::::{warning} MEDIAN_ABSOLUTE_DEVIATION is also non-deterministic. This means you can get slightly different results using the same data.

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