# `VAR_POP`

**Applies to:** ✅ Data 360 SQL ✅ Tableau Hyper API

Computes the population variance of input values (square of the population standard deviation).

## Syntax

```sql
var_pop(<expression>)
```

## Arguments

### Required

- `<expression>`: An expression of any numerical type.

## Returns

- `NUMERIC(38,6)` for integer-type or numeric arguments.
- `double precision` for floating-point arguments.

Returns NULL if the computation is meaningless.

## Considerations

- Uses N in the denominator (no Bessel's correction).
- Population variance is the square of `STDDEV_POP`.
- Use `VAR_SAMP` or `VARIANCE` for sample variance.
- Cast the input to `double precision` to get a `double precision` result.

## Examples

### Calculate Population Variance

Find the population variance of scores.

```sql
SELECT var_pop(score) AS score_variance
FROM test_results;
```

### Population Variance by Group

Calculate for each group.

```sql
SELECT class_id, var_pop(grade) AS grade_variance
FROM student_grades
GROUP BY class_id;
```

## Related Documentation

- [COVAR_SAMP/VAR_SAMP](/docs/data/data-cloud-query-guide/references/dc-sql-reference/covar-samp.md)
- [VARIANCE](/docs/data/data-cloud-query-guide/references/dc-sql-reference/variance.md)
- [STDDEV_POP](/docs/data/data-cloud-query-guide/references/dc-sql-reference/stddev-pop.md)
- [Aggregate Functions](/docs/data/data-cloud-query-guide/references/dc-sql-reference/aggregate.md)