I don't see why not. You would just create a calculate field that is the average of all unemployment rates, add that to your "Detail" (level of detail) shelf, and it should become available in your tooltips--if selecting states creates a filter/action of some kind, then only those states will be included in the average of unemployment rates. If you want to mock up a similar example using different measures in the Superstore data set, someone will be glad to show you how to set this up.
I got it to work in the crosstab, where I use the map as a filter, and the resulting crosstab does a Window_avg on Table down. That may suffice for now, but I still think it would be interesting to get this to show up in a tooltip
Sorry for resurrecting this one. But have you managed to find a solution for averages on a map?
I too can get it to work fine in a bar chart highlighting above and below using window_avg but not on a map.
Upload a dummy workbook if you want a real answer.
On Sunday, October 18, 2015, David Pires <