Null, chance, or normal variation

One rival you must always list says nothing happened: the swing sits inside the range your numbers bounce around anyway. Before hunting for a cause, ask whether this month's figure would look unremarkable next to the last two years of month-to-month noise.

One rival you must always list says nothing happened: the swing sits inside the range your numbers bounce around anyway. Before hunting for a cause, ask whether this month's figure would look unremarkable next to the last two years of month-to-month noise.

Example

You pull 24 months of shop revenue and find monthly swings of 20 to 35 percent are routine, with three past drops steeper than this one. A 30 percent fall is ordinary noise, so the algorithm, the price hike, and the competitor may all be explaining nothing.