See how a running total differs from a rate of change, using parcel deliveries...

https://mighty-wiki.win/index.php/Why_Does_the_Derivative_Not_Work_on_a_Pure_Transaction_History%3F

See how a running total differs from a rate of change, using parcel deliveries as an example. The article shows what each number means, why units matter, and how a daily rate over one week can tell a different story from the week’s total at work.