4 Replies Latest reply on Dec 14, 2012 11:11 AM by SandyHaaf

    Average Issues



      Average Issues


           I have a layout (report) that is grouped by an ID, Year and Month.  When we get down to the month grouping, it is doing an average of wind speed (NRG1) for each month.  At the end it averages all the months and then the grand summary it averages everything.  The issue is that when I do the calculations the averages don't add up?  The BIALKE Average should be closer to 8.86 and the Grand Average closer to 7.  Did I do something wrong?

           For the averages, I created a summary field using Average Of.

           I've attached the report so you can see the numbers and the layout design


           I did the same sort of report with summary field of Total and it worked fine.




        • 1. Re: Average Issues

               Are there cases where the field being averaged is empty? And in those cases, should that count as a zero in your average?

               When FileMaker summary fields or the Average function compute the mean, they ignore null values.


               values of 4 ; <null> ; 5 will produce a mean of 4.5 ( [4 + 5]/2 ), instead of a mean of 3 ( [4 + 0 + 5] / 3 ).

               If this is the case, put a zero in those fields if you want them treated as a zero value.

          • 2. Re: Average Issues

                 There are no null values and no zero values (at this time).

            • 3. Re: Average Issues

                   How do you need the average to be calculated?

                   FileMaker is calculating the average over all the records in your sorted group and over all the records in the entire found set. Each record is given equal "weight".

                   Might the average that you want be: ( OctoberAverage + NovemberAverage + DecemberAverage ) / 3 ??

              • 4. Re: Average Issues

                     OK, I get what is happening now and it makes sense!