# STDDEVP

## Returned Type

This function returns a number.

## Syntax and Details

STDDEVP(set_expression, optional_numeric_expression)

Where:

set_expression is an expression that evaluates to a set, typically a set of members or tuples.

optional_numeric_expression is a numeric-valued expression that the function evaluates for each set element.

Typically, this expression has the form [MEASURES].[measure_name]

If you do not specify a numeric expression, the system uses the measure used by the current result cell.

The function evaluates the numeric value for each element of the set and returns the population standard deviation of those values.

## Example

First, the following query shows two measure values for the members of the aged.decade level:

SELECT {MEASURES.[%COUNT],MEASURES.[encounter count]} ON 0, birthd.decade.MEMBERS ON 1 FROM patients Patient Count Encounter Count 1 1910s 80 5,359 2 1920s 227 12,910 3 1930s 567 33,211 4 1940s 724 38,420 5 1950s 1,079 46,883 6 1960s 1,475 57,814 7 1970s 1,549 49,794 8 1980s 1,333 35,919 9 1990s 1,426 29,219 10 2000s 1,406 20,072 11 2010s 134 1,346

Next, the following query shows the population standard deviations for these measures for the members of this level:

SELECT {MEASURES.[%COUNT],MEASURES.[encounter count]} ON 0, STDDEVP(birthd.decade.MEMBERS) ON 1 FROM patients Patient Count Encounter Count STDDEVP 552.44 17,544.98

Here, each value is the population standard deviation of the values in a column in the preceding query. For example, the Patient Count value is the population standard deviation of the Patient Count values in the preceding query.

For another example, we use the second argument for STDDEVP:

SELECT STDDEVP(birthd.decade.MEMBERS, MEASURES.[%COUNT]) ON 0 FROM patients STDDEVP 552.44

For additional, similar examples, see AVG.