ACC: Reporting the Median Value of a Group of Records

• Microsoft Access versions 1.0, 1.1, 2.0, 7.0, 97

SUMMARY

Novice: Requires knowledge of the user interface on single-user computers.

This article demonstrates how to create a report that shows the median value for a set of records. Note that a median value is the midpoint in an ordered set of values (the value above and below which there is an equal set of values), or the arithmetic mean of the two middle numbers if there is no one middle number.

MORE INFORMATION

The following sample report is based on the Orders table in the sample database Northwind.mdb (or NWIND.MDB in versions 1.x and 2.0). The report will group records by the CustomerID field, and will sort records within each group by the Freight field.

NOTE: In Microsoft Access 1.x and 2.0, there is a space in the Customer ID field name.

1. Open the sample database Northwind.mdb (or NWIND.MDB in version 2.0 or earlier) and create a new report based on the Orders table.



2. On the View menu, click Sorting And Grouping. Select CustomerID as the first field. Set GroupHeader and GroupFooter to Yes.



3. Select Freight as the second field. Select Ascending for the Sort Order.



4. If it is not displayed, choose Field List from the View menu. Drag the CustomerID field from the field list to the CustomerID header on the report.



5. Drag the Freight field to the detail section.



6. Add the following unbound controls to the CustomerID header:
   

   
         Name         Control Source
         -------------------------------
         IDCount      =Count(*)
         Half         =Int([IDCount]/2)
         Odd          =([IDCount] Mod 2) 

   
   NOTE: The Name property is called ControlName in version 1.x.



7. Add the following unbound controls to the detail section:
   
   NOTE: In the following example, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this example.
   

   
         Name         Control Source
         -------------------------------------------------------------
         Position     =1
         Arg1         =Val(IIf([Position]=([Half]+[Odd]),[Freight],0))
         Arg2:        =Val(IIf([Odd]=0,IIf([Position]=([Half]+_
                         [Odd]+1),[Freight],0),0)) 

   
   Set the RunningSum property to Over Group for each of the text box controls in this section except for the Freight text box control.



8. Add the following unbound control to the CustomerID Footer:
   

   
       Name         Control Source
       --------------------------------------------------
       Median    =IIF([Odd]=0,([Arg1]+[Arg2])/2,[Arg1]) 




9. Save and run the report.

Keywords          : kbusage RptOthr 
Version           : 1.0 1.1 2.0 7.0 97
Platform          : WINDOWS 
Issue type        : kbinfo 

Last Reviewed: March 26, 1999