Reference Line Exclude Value

[Bob_J]

Does anyone know how to create a reference line that is the average of all values in the dimension except the selected one?  For example, I have a bar chart with the quantities of each serial number.  When I select a serial number, I want to show a reference line that is the average of the quantities of all serial numbers except the selected one. 

[Lisa_P]

For your reference line expression, you use Set Analysis to exclude the selected value

eg  {<[serial number]=-{<$(=GetSelectedValue([serial number]))>}>}Avg(Aggr(Count([serial number), [serial number))