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

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stddevPop

The result is equal to the square root of varPop.

Aliases: STD, STDDEV_POP.

:::note This function uses a numerically unstable algorithm. If you need numerical stability in calculations, use the stddevPopStable function. It works slower but provides a lower computational error. :::

Syntax

stddevPop(x)

Parameters

• x: Population of values to find the standard deviation of. (U)Int*, Float*, Decimal*.

Returned value

Square root of standard deviation of x. Float64.

Example

Query:

DROP TABLE IF EXISTS test_data;
CREATE TABLE test_data
(
    population UInt8,
)
ENGINE = Log;

INSERT INTO test_data VALUES (3),(3),(3),(4),(4),(5),(5),(7),(11),(15);

SELECT
    stddevPop(population) AS stddev
FROM test_data;

Result:

┌────────────stddev─┐
│ 3.794733192202055 │
└───────────────────┘