# Statistical Functions

#### <mark style="color:purple;">STDDEV(</mark>  expression  <mark style="color:purple;">)</mark>

Returns the sample standard deviation, within the input group of values.

```sql
select stddev(colB) from table1
```

#### <mark style="color:purple;">STDDEV\_POP(</mark>  expression  <mark style="color:purple;">)</mark>

Returns the population standard deviation, which is the square root of the population variance, from the input group of values.

```sql
select stddev_pop(colB) from table1
```

#### <mark style="color:purple;">PERCENTILE\_CONT(</mark> \<percentile> ) WITHIN GROUP (ORDER BY \<expression> \[ ASC | DESC ] <mark style="color:purple;">)</mark>

Returns the linear interpolated value that would fall into the given **\<percentile>** value with respect to the specified sort direction.

```sql
select percentile_cont(0.5) within group1 (order by colA asc) from table1
```

#### <mark style="color:purple;">APPROX\_QUANTILES(</mark>  \<expr>,   number  <mark style="color:purple;">)</mark>

```sql
select approx_quantiles(colA, 4)
```

Returns the approximate boundaries for a group of `<expr>`values, where `number` represents the number of quantiles to create. This function returns an array of `number` + 1 element, where the first element is the approximate minimum and the last element is the approximate maximum.