I have data on returns to a portfolio that is structured as follows:
I rank each company in my portfolio according to its market value. I create ten groups, or deciles, based on this ranking. Group 1 is the smallest companies and group 10 is the largest. "Group" is a dimension in Tableau. For each group I have a figure for profit/loss earned, this is my measure. This information is available quarterly, stretching back a number of years. So I also have a dimension called quarter. What I am trying to do is to create an average of profit/loss across multiple groups (dimensions). For instance, for each quarter I'd like to display the average profit/loss for groups 1 through 5, groups 6 through 8, and groups 9 through 10. This would leave me displaying three data points for each quarter.