ClickHouse/docs/en/sql-reference/aggregate-functions/reference/varsamp.md

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slug: /en/sql-reference/aggregate-functions/reference/varsamp
sidebar_position: 33
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# varSamp

Calculates the amount `Σ((x - x̅)^2) / (n - 1)`, where `n` is the sample size and `x̅`is the average value of `x`.

It represents an unbiased estimate of the variance of a random variable if passed values from its sample.

Returns `Float64`. When `n <= 1`, returns `+∞`.

Alias: `VAR_SAMP`.

:::note
This function uses a numerically unstable algorithm. If you need [numerical stability](https://en.wikipedia.org/wiki/Numerical_stability) in calculations, use the `varSampStable` function. It works slower but provides a lower computational error.
:::
[docs] split aggregate function and system table references (#11742) * prefer relative links from root * wip * split aggregate function reference * split system tables 2020-06-18 08:24:31 +00:00			`---`
add slugs 2022-08-28 14:53:34 +00:00			`slug: /en/sql-reference/aggregate-functions/reference/varsamp`
Removed /ja folder, cleaned up /ru markdown 2022-04-09 13:29:05 +00:00			`sidebar_position: 33`
[docs] split aggregate function and system table references (#11742) * prefer relative links from root * wip * split aggregate function reference * split system tables 2020-06-18 08:24:31 +00:00			`---`

Remove H1 anchor tags from docs 2022-06-02 10:55:18 +00:00			`# varSamp`
[docs] split aggregate function and system table references (#11742) * prefer relative links from root * wip * split aggregate function reference * split system tables 2020-06-18 08:24:31 +00:00
			Calculates the amount `Σ((x - x̅)^2) / (n - 1)`, where `n` is the sample size and `x̅`is the average value of `x`.

Small typo fix 2022-06-14 17:26:44 +00:00			`It represents an unbiased estimate of the variance of a random variable if passed values from its sample.`
[docs] split aggregate function and system table references (#11742) * prefer relative links from root * wip * split aggregate function reference * split system tables 2020-06-18 08:24:31 +00:00
			Returns `Float64`. When `n <= 1`, returns `+∞`.

Add STD alias to stddevPop function for MySQL compatibility 2023-09-07 03:46:27 +00:00			Alias: `VAR_SAMP`.

			`:::note`
Removed /ja folder, cleaned up /ru markdown 2022-04-09 13:29:05 +00:00			This function uses a numerically unstable algorithm. If you need [numerical stability](https://en.wikipedia.org/wiki/Numerical_stability) in calculations, use the `varSampStable` function. It works slower but provides a lower computational error.
Small typo fix 2022-06-14 17:26:44 +00:00			`:::`