### PopulationVariance (fld), PopulationVariance (fld, condFld), PopulationVariance (fld, condFld, cond), PopulationVariance (x)

Basic and Crystal syntax.

##### Arguments

- fld is any valid database or formula field that can be evaluated by the function.
- condFld is a field used to group the values in fld by.
- cond is a String indicating the type of grouping for condFld. You only specify this argument when condFld is a Date, Time, DateTime or Boolean field. For more information on the valid strings for this argument, see Conditions for summary functions.
- x is an array of values that can be evaluated by the function being used.

##### Returns

Fractional Number

##### Action

Enables you to find the population variance of a set of values in your report. For example:

- You can calculate the grand total population variance for all values in a field. For information on this kind of summary, see SummaryFunction (fld).
- You can calculate the population variance for all values within a group (for example, sales grouped by the state that they come from). For information on this kind of summary, see SummaryFunction (fld, condFld).
- You can calculate the population variance for all values within a group in which grouping is controlled by changes in a date or Boolean field (for example, sales grouped by the month in which they were made). For information on this kind of summary, seeSummaryFunction (fld, condFld, cond).
- If you specify a set of individual values, you can compute the population variance of the values in the set. For information on this kind of summary, see Array summary functions (x).

##### Examples

The following examples are applicable to both Basic and Crystal syntax:

For examples of each PopulationVariance function, click on the corresponding summary function.

`PopulationVariance({file.CENSUS})`

Calculates the variance of all values in the Census field.

`PopulationVariance({file.RESULTS}, {file.PROCEDURE})`

Calculates the population variation for each group of laboratory test results in the Results field. The test results are separated into groups whenever the value in the Procedure field changes.

`PopulationVariance({file.SCORES}, {file.NATURALIZED}, "any change")`

Groups values in the Scores field based on whether or not the test taker is a naturalized citizen, and calculates the population variance for each group of scores.

The following examples are applicable to Crystal syntax:

`PopulationVariance({file.SCORES}, {file.TEACHERS}) % PopulationVariance({file.TEACHERS})`

Groups values in the Scores field by teacher, and calculates the population variance for each teacher group as a percentage of the population variance of the values for the entire report (for all teachers listed).

`PopulationVariance([2,4,6,8,10])`

Returns 8.

##### Comments

Population variance is calculated using the following technique:

- It calculates the average (mean) value for the items in the population.
- It subtracts the average value from the value of each item.
- It squares the difference for each item.
- It adds the squared differences for all of the items in the population.
- It divides the sum by the number of items in the population (N). The result is the population variance. Compare this final step to the Variance (fld), Variance (fld, condFld), Variance (fld, condFld, cond), Variance (x).

Note: Using this function in a formula forces the formula to be evaluated at print time.

For more information on evaluation time considerations, see Evaluation Time functions.

Seagate Software, Inc. http://www.seagatesoftware.com Please send comments to: techpubs@seagatesoftware.com