Calculate the sample variance of a data set. Unlike [`varSamp`](../reference/varsamp.md), this function uses a numerically stable algorithm. It works slower but provides a lower computational error.
**Syntax**
```sql
varSampStable(x)
```
Alias: `VAR_SAMP_STABLE`
**Parameters**
-`x`: The population for which you want to calculate the sample variance. [(U)Int*](../../data-types/int-uint.md), [Float*](../../data-types/float.md), [Decimal*](../../data-types/decimal.md).
**Returned value**
- Returns the sample variance of the input data set. [Float64](../../data-types/float.md).
**Implementation details**
The `varSampStable` function calculates the sample variance using the same formula as the [`varSamp`](../reference/varsamp.md):
$$
\sum\frac{(x - \text{mean}(x))^2}{(n - 1)}
$$
Where:
-`x` is each individual data point in the data set.
-`mean(x)` is the arithmetic mean of the data set.
-`n` is the number of data points in the data set.
**Example**
Query:
```sql
DROP TABLE IF EXISTS test_data;
CREATE TABLE test_data
(
x Float64
)
ENGINE = Memory;
INSERT INTO test_data VALUES (10.5), (12.3), (9.8), (11.2), (10.7);
SELECT round(varSampStable(x),3) AS var_samp_stable FROM test_data;
