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> 计算序列的样本偏度。

# skewSamp

<div id="skewSamp">
  ## skewSamp
</div>

引入版本：v20.1.0

计算一个序列的[样本偏度](https://en.wikipedia.org/wiki/Skewness)。

如果传入的值构成某个随机变量的样本，则该值表示该随机变量偏度的无偏估计。

**语法**

```sql theme={null}
skewSamp(expr)
```

**参数**

* `expr` — 返回数值的表达式。[`Expression`](/zh/reference/data-types/special-data-types/expression)

**返回值**

返回给定分布的偏度。如果 `n <= 1` (`n` 为样本大小) ，则函数返回 `nan`。[`Float64`](/zh/reference/data-types/float)

**示例**

**对称分布**

```sql title=Query theme={null}
SELECT skewSamp(number) FROM numbers(100);
```

```response title=Response theme={null}
┌─skewSamp(number)─┐
│                0 │
└──────────────────┘
```

**右偏态分布**

```sql title=Query theme={null}
SELECT skewSamp(x) FROM (SELECT pow(number, 2) AS x FROM numbers(10));
```

```response title=Response theme={null}
┌────────skewSamp(x)─┐
│ 0.5751042382747413 │
└────────────────────┘
```