Using Summary Field in Calculation to Produce Averages
I am having a total brain fart and can not figure out how to produce an average of totals...
I have a Summary Field that totals all line items on work orders, thus allowing me to produce sub summary reports and graphs that show the total parts spent on each vehicle. What I want to do is use that Summary Field total to calculate the average total per vehicle. Thus, giving me the ability to graph all vehicles to see if they fall above or below this average. So if I create another summary field using average, it won't let me select my other summary field used to total. If I select the line item field, then I get an average of all line items, not by vehicle.
What is the best approach to first total parts by vehicle, then calculate an average of those totals....