Sometimes when you calculate the "compare to previous" number manually, it can appear to be incorrect.
This normally means that you're calculating the number in a different way than our system.
When you compare one calendar month to another in our system, we compare against the previous number of calendar month days.
So, for example, if your reporting period is the month March, which has 31 days, we're comparing against the previous 31 day period. We're NOT comparing against the calendar month of February. The month of March (March 1 through 31) would be compared against January 29 - February 28th to get a matching 31 day period.
This provides a more accurate and useful comparison in most cases.