`expr` — [Expression](../../../sql-reference/syntax.md#syntax-expressions) returning a number.
**Returned value**
The kurtosis of the given distribution. Type — [Float64](../../../sql-reference/data-types/float.md). If `n <= 1` (`n` is a size of the sample), then the function returns `nan`.
**Example**
``` sql
SELECT kurtSamp(value) FROM series_with_value_column