A period-over-period comparison puts a number beside the same number from an earlier period and shows the difference, usually as a percentage. Month over month compares this month with last; year over year compares this month with the same month a year ago; week over week and quarter over quarter follow the same idea. The comparison is what turns “revenue was 1.2M” into “revenue was 1.2M, up 6% on last month and down 2% on last year”.
Comparisons matter because a number on its own means almost nothing. A restaurant group’s Saturday revenue looks fine until it is set against the same Saturday last year and turns out to be 9% down. A school’s enrolment figure only makes sense against last September. Year over year is the workhorse for seasonal businesses, because it removes the seasons; month over month is better for spotting a change that has just started.
The traps are partial periods and calendar shifts. Comparing the first ten days of this month with all of last month is a common mistake, as is comparing a month with five weekends against one with four. Rule of thumb: compare like with like — same number of days, same number of trading days, or “month to date vs same days last month” — and label the comparison on the page so readers know which it is.
In Klayara, every headline figure can show its comparison to the previous period or the same period last year, with the change in percentage and colour, and comparisons carry into scheduled reports. See dashboards and formulas for custom comparisons.