Average an Averaged Sub-Summary?

[Rich S]

Greets, all:

 

I'm creating a report where I need to average each heading's average but I'm scratching my head raw trying to get it to work. (Please refer to the attached.)

 

For example, under Content Specialist, I want to average 2.13 and 2.71 which should equal 2.42 (4.84 / 2 = 2.42) but FileMaker has other plans and spat out 3.03...which is a result of taking all the gazillion records in the found set and averaging them out instead of averaging just the two (sub-summarized) numbers.

 

I "get" that I need to create a new sub-summary but how should I code the (new) summary field so I get the average of the items listed under each heading?

 

TIA for your help!

Rich

[comment]

For example, under Content Specialist, I want to average 2.13 and 2.71 which should equal 2.42 (4.84 / 2 = 2.42)

 

Are we looking at the same picture? I see 3.13 and 2.71. Anyway, why would you want to average the averages? It skews the data.

[Rich S]

Yup, it's 3.13. I didn't have my reading/computer glasses handy when I wrote that. Sorry!

 

Y'know, I asked the very same question but that's what my boss wants so that's what she gets. :|

[comment]

Well, she's not my boss, so that's not good enough for me. Perhaps you should show her the following example:

 

A school has two classes. There are 9 students in the first class and all of them have a perfect score of 100. The other class is a remedial class; it has only one student with a score of 0.

 

According to your boss, the overall school average should be calculated as follows:

 

• Class 1 average = 9 * 100 / 9 = 100;

• Class 2 average = 1 * 0 / 1 = 0;

School average = ( 100 + 0 ) / 2 = 50

 

which is of course a complete nonsense, because in fact the overall school average is = ( 9 * 100 + 1 * 0 ) / ( 9 + 1 ) = 90 i.e. "a result of taking all the gazillion records in the found set and averaging them out instead of averaging just the two (sub-summarized) numbers".

 

Now I'll make you a deal: show me a case where the average of averages has a meaning and I'll show you how to calculate it.

[LaRetta]

What a perfect example.

[Rich S]

GREAT example! Thanks! I'm supposed to meet with her again about this Monday or possibly Tuesday, so stay tuned.

[Rich S]

Sorry I didn't get back to y'all yesterday.

 

I presented your outstanding example, Comment, and she "got it", so no averaging of averages. : )

[comment]

Well, the example is rather trivial - but it's encouraging to hear that common sense prevailed, even in the education sector. 

 

Just for the record: there are special cases where the average of averages does have a meaning.