Computes the statistical variance of a population consisting of a numeric-expression, as a DOUBLE.
Parameter |
Description |
---|---|
expression |
The expression (commonly a column name) whose population-based variance is calculated over a set of rows. |
DOUBLE
Computes the population variance of the provided value expression evaluated for each row of the group or partition (if DISTINCT was specified, then each row that remains after duplicates have been eliminated), defined as the sum of squares of the difference of value expression, from the mean of value expression, divided by the number of rows (remaining) in the group or partition.
Population-based variances are computed according to the following formula:
SQL—Vendor extension to ISO/ANSI SQL grammar.
Sybase—Not supported by Adaptive Server Enterprise.
SELECT year( ShipDate ) AS Year, quarter( ShipDate ) AS Quarter, AVG( Quantity ) AS Average, VAR_POP( Quantity ) AS Variance FROM SalesOrderItems GROUP BY Year, Quarter ORDER BY Year, Quarter
Year |
Quarter |
Average |
Variance |
---|---|---|---|
2000 |
1 |
25.775148 |
203.9021 |
2000 |
2 |
27.050847 |
225.8109 |
... |
... |
... |
... |