**StDev, StDevP Functions (SQL Only)**

__See Also__ __Example__ >Low

**Description**

Return estimates of the standard deviation for a population or a population sample represented as a set of values contained in a specified field on a query.

**Syntax**

**StDev(** *expr* **)**

**StDevP(** *expr* **)**

**Remarks**

StDevP evaluates a population, and StDev evaluates a population sample.

The StDev and StDevP functions use the following argument.

**Argument Description**

*expr* String expression identifying the field that contains the numeric data you want to evaluate, or an expression that performs a calculation using the data in that field. Operands in *expr* can include the name of a table field, or a Visual Basic function (which can be intrinsic but not a user-defined function or one of the other domain aggregate or SQL aggregate functions).

If the underlying query contains fewer than two records (or no records, for StDevP), these functions return a **Null** (which indicates that a standard deviation can't be calculated).