VarP DataWindow expression function
Description
Calculates the variance for the specified column. The variance
is the square of the standard deviation.
Syntax
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<span>VarP</span> ( <span>column</span> { FOR <span>range</span> { DISTINCT { <span>expres1</span> {, <span>expres2</span> {, ... } } } } } ) |
|
Argument |
Description |
|---|---|
|
column |
The column for which you want the variance |
|
FOR range (optional) |
The data that will be included in the
For Crosstabs, specify CROSSTAB for range:
For Graph and OLE objects, specify one of the following:
|
|
DISTINCT (optional) |
Causes VarP to consider |
|
expresn (optional) |
One or more expressions that you want |
Return Values
Double or decimal if the arguments are decimal. Returns the
variance for column. If you specify group, Var returns
the variance for column within range.
Usage
If you specify range, VarP returns
the variance for column within range.
If you specify DISTINCT, VarP returns the variance
for the distinct values in column, or if you
specify expresn, 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
VarP assumes that the values in column are
the values in all rows in the column in the database table. If you
did not select all the rows in the column in the SELECT statement,
use Var to compute an estimate of the variance
of a sample.
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
retrieved all rows in the database table. VarP is
intended to work with a full set of data, not a subset.
This expression returns the variance of the values in the
column named salary:
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<span>VarP</span>(salary) |
This expression returns the variance of the values
in group 1 in the column named salary:
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<span>VarP</span>(salary for group 1) |
This expression returns the variance of the values
in column 4 on the page:
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<span>VarP</span>(#4 for page) |
This expression entered in the Value box on the Data
property page in the graph’s property sheet returns the
variance of the values in the quantity column in the graph:
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<span>VarP</span>(quantity for graph) |
This expression for a computed field in a crosstab
returns the variance of the values in the quantity column in the
crosstab:
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<span>VarP</span>(quantity for crosstab) |
Assuming a DataWindow object displays the order number,
amount, and line items for each order, this computed field returns
the variance of the order amount for the distinct order numbers:
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<span>VarP</span>(order_amt for all DISTINCT order_nbr) |