See how a running total of parcels differs from a rate of change: one tells how...

https://thoughtminty.com/s/xoowvo7xXqtbB0_JmHigE

See how a running total of parcels differs from a rate of change: one tells how many have arrived so far, the other how many arrive per hour. The article uses clear units and time windows to make both numbers useful in a shift report.