VarP
DataWindow expression function
Description
Calculates the variance for the specified column. The variance is
the square of the standard deviation.
Syntax
|
1 |
VarP ( column { FOR range { DISTINCT { expres1 {, expres2 {, ... } } } } } ) |
|
Argument |
Description |
|---|---|
|
column |
The column for which you want the variance of the |
|
FOR range (optional) |
The data that will be included in the variance. For
For Crosstabs, specify CROSSTAB for
For Graph and OLE objects, specify one of
|
|
DISTINCT (optional) |
Causes VarP to consider only the distinct values in |
|
expresn (optional) |
One or more expressions that you want to evaluate to |
Return value
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:
|
1 |
VarP(salary) |
This expression returns the variance of the values in group 1 in the
column named salary:
|
1 |
VarP(salary for group 1) |
This expression returns the variance of the values in column 4 on
the page:
|
1 |
VarP(#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:
|
1 |
VarP(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:
|
1 |
VarP(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:
|
1 |
VarP(order_amt for all DISTINCT order_nbr) |
See also