Median/Average with Set Analysis

[#1]

So here's my situation:

I have two charts.

A 7 day rolling:

And a 30 day rolling.  What is visible are created/resolved tickets and a daily average and daily median calculation (done using set analysis).

However when I try to calculate a 7 day average and median, the numbers are incorrect as compared to doing them by hand.

Here is the set analysis I'm using with my calculations as displayed:

Avg({1<[Project ID] = {10320}>} DaysToResolve)

Now I'm not entirely sure those numbers are right either as the average on Oct-2 on the chart is 11.3 and when I calculate by hand it comes out to 21.25.

How do I properly calculate the individual days, and a 7 day average for what is displayed?

[Gysbert_Wassenaar]

Perhaps this document helps: Calculating rolling n-period totals, averages or other aggregations