When finding YoY Difference using a table calculation, the best way around not having a blank column for 2011 is to create two separate sheets and place them on a dashboard together. One sheet will have the values for both years, and the other sheet will have only the difference.
Hope this helps!
When you say one sheet will have the values and one will only have the difference - is there a way to just import the data values and calculate the difference in tableau? Or do you mean I need to calculate the difference outside of tableau and import those numbers?
I assume the second? I can't see a way to calculate the difference in tableau outside of using a table calculation with both years, but then you get a blank year.