1 of 1 people found this helpful
How did it work when you applied the calculation in your viz?
When you created a calculated field in tableau it is adding a column to the underlying table that supports each viz (like a column in an excel spreadsheet)
you formula will place a value "Jan" etc in the field of that chart that corresponds to the condition in your IF statement AND a NULL in any field that does not meet any of the conditions (if that makes sense)
So now to your question - you don't need to create a set - you have "Tagged" each record (think row) that met the condition - so if you drag Month to the viz it will work as if you created a group --- you can use MONTH in calculations, filters etc
If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution. Thank you.