InterSystems MDX Reference
STDDEVP


Returns the population standard deviation of a given expression, across all elements of a set.
This function returns a
number.
STDDEVP(set_expression, optional_numeric_expression)


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.
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.