Basic Scatter diagram/set analysis question

[nicktodd]

I made a small app (simplified version attached) to display student marks for a module versus their average across all modules - calculated by set analysis function

Avg({$<Module=>} Mark)

The issue is that, because of the set analysis function, in selecting a module (for example, M4) all students are shown on the diagram legend even though some students (E and F) did not take that module. I'd like to exclude students who didn't take the module so that a user may export the scatter diagram to Excel and see students for that module only.

I've a feeling there must be a very simple solution to this but I can't see it!

Thanks

[nicktodd · Accepted solution]

As I suspected the answer was staring me in the face!

All I did was:

=if(not IsNull(Mark),Avg({$<Module=>} Mark))

and now I get the right answer for only those students studying a module. Doh!

Nick