Taking Average of Calculated Column

Hi All,

I created a lead time report and want to add a card that shows the average lead time.  It's a very basic report where I just use a calculated column that takes the difference between a start date and completion date and added a table that lists each order, release date, and lead time.  The table contains grand totals at the bottom and the one for lead time shows what appears to be a random number (it isn't the sum, average, or count).  The card where I added the lead time calculation shows a different value and I have no idea where that number came from either.  There isn't an option to change the card to sum, total, or count either.

Why can't I change the calculation method in the card?

One thing worth mentioning is that the table I'm pulling from is an iterative refresh where it shows each work order's status every day, and the way I calculate lead time is by using the min()s function with an allexcept() filter that filters to only look at rows with matching work orders and rows that contain the status designators that indicate when a job is started and when a job is completed.  Therefore, rows containing the start designator show the start date but not the complete date, and rows with the complete status designator show complete date but not start dates.  What I then do is a measure where I take the difference btw the two columns.  When I put this in a table, each work order contains a single row that includes both the start and complete date, and the lead time calculations do work.