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50 lines
1.2 KiB
Markdown
50 lines
1.2 KiB
Markdown
---
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slug: /en/sql-reference/aggregate-functions/reference/stddevpopstable
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sidebar_position: 30
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---
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# stddevPopStable
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The result is equal to the square root of [varPop](../../../sql-reference/aggregate-functions/reference/varpop.md). Unlike [`stddevPop`](../reference/stddevpop.md), this function uses a numerically stable algorithm. It works slower but provides a lower computational error.
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**Syntax**
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```sql
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stddevPopStable(x)
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```
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**Parameters**
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- `x`: Population of values to find the standard deviation of. [(U)Int*](../../data-types/int-uint.md), [Float*](../../data-types/float.md), [Decimal*](../../data-types/decimal.md).
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**Returned value**
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Square root of standard deviation of `x`. [Float64](../../data-types/float.md).
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**Example**
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Query:
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```sql
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DROP TABLE IF EXISTS test_data;
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CREATE TABLE test_data
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(
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population Float64,
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)
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ENGINE = Log;
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INSERT INTO test_data SELECT randUniform(5.5, 10) FROM numbers(1000000)
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SELECT
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stddevPopStable(population) AS stddev
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FROM test_data;
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```
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Result:
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```response
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┌─────────────stddev─┐
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│ 1.2999977786592576 │
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└────────────────────┘
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```
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