I have calculated a 4-year difference however there are some schools without a difference. Tableau is taking the average of year 4 minus the average of year 1. However, I need the average difference of only those schools that have a difference. How do I accomplish this?
I'm unsure I understand what the issue is. If there is no value for the '4-Year Diff' calculation then it shouldn't show? To do this, right click on 4-Year Diff on the measure values card and select Filter. Then, click OK (make sure the 'Include Null Values' box is not checked).
Hope this helps!