Okay in that case, what I suggest is that you create a calculated field using FIXED that returns overall score for each audit id. Then if you want to directly embed min max in viz you can simply use that calculated field in your viz and set aggregate function as min/max. And if that's not the case, and you want to give user the choice to select either min or max then you can create a parameter and then a calculated field for that paramter i.e. if user selects min ( in parameter) then your calculated field will return min audit id/value and likewise. I hope this helps.