How to properly average the differences in dates by month?

Caroline Blanchard

We are looking to create a new measure which will subtract the dates 'Requisition Line Approval Date' from 'PO Creation Fiscal Date'. Then we would like to Average the result by a monthly basis. The goal would be to have a bar chart with monthly average for the difference of the dates.

We are able to get the proper result only if 'PO Creation Fiscal Date' is included in a table and only the grand total shows the proper average.

The proper average we're looking for is the '-7.67' in the left table versus the '0.51' on the right table. Seems like the only way to get the average is to have the dates included, is there any way to get the right table to show the proper value without having the date field?

Here is the calculation being used. (The ExtractDay is used to convert to a timestamp)