Anytime you create filled maps with certain dimension members (could be country/state names) having NULL values (missing values), Tableau tends to color or highlight the entire region regardless of whether countries/states have values or not - resulting to views which can be misleading to users.
This is what am talking about…
(In this filled map, the highlighted states contain NULL values, however by the look of the color legend they have been represented as if they contain values – which is misleading to users)
How can we fix this?
We can fix this by simply showing the states containing NULL values in a different color.
To do that, create a simple filled map.
Duplicate the view (map)
Make the view dual axis…
Create a calculation that will return TRUE for cases where states have NULL values (for this data am using Sales).
Add this calculation to color shelf of the second view (chart), ensure the selection under marks card is ‘Map’.
Assign the appropriate colors.
On the color legend hide the item ‘False’.
And there we’ve a more interpretable view which users can easily tell the states with null values – take the right action without being misled by the view.
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