Question about the best way to create Margin of Error as a fact?
Originally I had created a new logical column off of a database fact for Margin of Error by selecting Derived from existing columns using expression and then the calculation: 1.96(STDDEV(FACT COLUMN)) / (sqrt(COUNT(FACT COLUMN)))/ Which works mostly fine. The only difference I can tell is that I can't use the column filter function like I can if I use Derived from physical mappings. But besides that the data recalculates correctly if I add new columns to the report.
But that is my question, should I use the option Derived from physical mappings instead and if so, how do I make it work? I got the calculation to work, but I left the aggregation as None. When I tried out the new column in Answers, the value that is returned is correct for all the data, but if I add any other columns, the data remains the same. So it doesn't recalc like it does with using Derived from physical mappings.
Any thoughts on how I should be doing this, am I doing it right?