stddev

stddev_pop

Computes the population standard deviation over each aggregate.

Syntax

stddev_pop([DISTINCT] arith_expr)

Arguments

arith_expr

The arithmetic expression on which the standard deviation is to be computed.

Description

This function computes the population standard deviation for each aggregate from the value of arith_expr for each row in the aggregate. The value is computed as the square root of the population variance (var_pop).

If distinct is specified, duplicate values are not included in the computation.

Example

open nsfawards;

select orgid, count(*), sqrt(var_pop(amount)), stddev_pop(amount) from nsforg natural join award
     group by 1 having count(*) >= 5000;

orgid    count(*) sqrt(var_pop(amount)) stddev_pop(amount)
CHE          5702      576910.103367379   576910.103367379
DMI          6526       262149.54332253    262149.54332253
DMR          5381       2423104.2772563    2423104.2772563
DMS          9910         502892.258401      502892.258401
DUE          8810      409907.329019828   409907.329019828
EAR          7256      1622729.36495319   1622729.36495319
IBN          5438       256969.90628445    256969.90628445
INT          5954       601498.65086807    601498.65086807
OCE          5998      3979661.75510613   3979661.75510613
SES          5944      360739.896551804   360739.896551804