Var DataWindow expression function

Description

Calculates an estimate of the variance for the specified column.
The variance is the square of the standard deviation.

Syntax

<span>Var</span> ( <span>column</span> { FOR <span>range</span> { DISTINCT { <span>expres1</span> {, <span>expres2</span>  {, ... } } } } } )

1	<span>Var</span> ( <span>column</span> { FOR <span>range</span> { DISTINCT { <span>expres1</span> {, <span>expres2</span> {, ... } } } } } )

Argument	Description
column	The column for which you want an estimate for the variance of the values in the rows. Column can be the column name or the column number preceded by a pound sign (#). Column can also be an expression that includes a reference to the column. The datatype of column must be numeric.
FOR range (optional)	The data to be included in the estimate of the variance. For most presentation styles, values for range are: ALL – (Default) The estimate of the variance for all rows in column. GROUP n – The estimate of the variance for rows in column in the specified group. Specify the keyword GROUP followed by the group number: for example, GROUP 1. PAGE – The estimate of the variance for the rows in column on a page. For Crosstabs, specify CROSSTAB for range: CROSSTAB – (Crosstabs only) The estimate of the variance for all rows in column in the crosstab. For Graph and OLE objects, specify one of the following: GRAPH – (Graphs only) The estimate of the variance for rows in column in the range specified for the Rows option. OBJECT – (OLE objects only) The estimate of the variance for rows in column in the range specified for the Rows option.
DISTINCT (optional)	Causes Var to consider only the distinct values in column when determining the variance. For a value of column, the first row found with the value is used and other rows that have the same value are ignored.
expresn (optional)	One or more expressions that you want to evaluate to determine distinct rows. Expresn can be the name of a column, a function, or an expression.

Return Values

Double or decimal if the arguments are decimal. Returns an
estimate for the variance for column. If you
specify group, Var returns
an estimate for the variance for column within group.

Usage

If you specify range, Var returns
an estimate for the variance for column within range.
If you specify DISTINCT, Var returns the variance
for the distinct values in column, or if you
specify expresn, the estimate for the variance
of the rows in column where the value of expresn is
distinct.

For graphs and OLE objects, you do not select the range when
you call the function. The range has already been determined by
the Rows setting on the Data property page (the Range property),
and the aggregation function uses that range.

Settings for Rows include the following:

For the Graph or OLE presentation
style, Rows is always All.
For Graph controls, Rows can be All, Page, or Group.
For OLE controls, Rows can be All, Current Row,
Page, or Group. The available choices depend on the layer the control
occupies.

Estimating variance or calculating actual variance

Var assumes that the values in column are
a sample of the values in rows in the column in the database table.
If you select all rows in the column in the SELECT statement,
use VarP to compute the variance of a population.

Not in validation rules or filter expressions

You cannot use this or other aggregate functions in validation
rules or filter expressions.

Using an aggregate function cancels the effect of setting
Retrieve Rows As Needed in the painter. To do the aggregation, a DataWindow object always retrieves
all rows.

Examples

These examples all assume that the SELECT statement
did not retrieve all of the rows in the database table. Var is
intended to work with a subset of rows, which is a sample of the
full set of data.

This expression returns an estimate for the variance of the
values in the column named salary:

<span>Var</span>(salary)

1	<span>Var</span>(salary)

This expression returns an estimate for the variance
of the values in the column named salary in group 1:

<span>Var</span>(salary for group 1)

1	<span>Var</span>(salary for group 1)

This expression entered in the Value box on the Data
property page in the graph’s property sheet returns an
estimate for the variance of the values in the quantity column in
the graph:

<span>Var</span>(quantity for graph)

1	<span>Var</span>(quantity for graph)

This expression for a computed field in a crosstab
returns an estimate for the variance of the values in the quantity
column in the crosstab:

<span>Var</span>(quantity for crosstab)

1	<span>Var</span>(quantity for crosstab)

Assuming a DataWindow object displays the order number,
amount, and line items for each order, this computed field returns
the estimate for the variance of the order amount for the distinct
order numbers:

<span>Var</span>(order_amt for all DISTINCT order_nbr)

1	<span>Var</span>(order_amt for all DISTINCT order_nbr)

Connection Information

Var – PB Docs 125