My Average Line on my Scatter Chart is set to use a Volume YoY % measure ( :=SUM ( TY VOL ) / SUM ( LY VOL ) - 1 ).
Under Details I have the Business dimension, so my Scatter is showing YOY % Volume by Business.
However, my Average Line is displaying the arithmetic mean of the individual Business YoY %'s instead of the value returned by the YoY % measure. So the Average Line is using my measure, but instead of taking its evaluated value (given what's visible in the scatter) its simply averaging each YoY % for each visible Business.
How can I achieve an Average Line which uses the correct measure value? (this looks like a bug).
Firstly, thank you for taking the time to advise! I really appreciate it.
Yes I have been trying to think of a suitable DAX formula to achieve the result I wanted, but the scatter at present doesn't allow us to use any other measures than those already plotted on the scatter.
An alternative would be to allow the user to specify that a measure being used by an Average Line is of type ratio so it would compute its value appropriately.
And yes it was unfair of me to describe it as a bug since I can see why it behaves so; for example if I put [2016 Weeks] on the scatter and add Average Line, it will give me correct average.
The idea you found was posted by me. Scatter plots are really powerful visualisations and I hope in future releases they allow us to customise them more. For now I'll continue to use Median Line instead on scatter. At least median is arguably more representative of the 'average'.
Thanks for the helpful reminder about iterator functions!