Finding the Top N Within a Category

Option 1: Use INDEX()

1. Select Analysis > Create Calculated Field. 
2. Name the calculation (in this example, the calculation is named Index) enter the following formula, then click OK:
   INDEX()
3. In the Measures pane, right-click Index and select Convert to Discrete. 
4. Place Index on Rows, between Region and Sub-Category. 
5. Right-click Index on Rows and select Edit Table Calculation.
6. Under Compute Using, select Specific Dimensions. 
7. Under Restarting Every, select Region.
8. Under Sort Order, select Custom and enter the following options: 
   Sales Sum Descending
   
   
9. Ctrl+Click Index on Rows and place it on Filters. Click OK.
10. On the Filters shelf, right-click Index and select Continuous. 
11. In the Filter dialog box, type the range of values for your top N, then click OK. 

Option 2: Use RANK()