<b>Daily RPM swings ±20% are noise. You need 14+ days to read a change.</b>

<b>Daily RPM swings ±20% are noise. You need 14+ days to read a change.</b>

RPM variance by window, illustrative:
— 1 day ±21% ▮▮▮▮▮▮ (daypart, weekday, one big bid)
— 3 days ±12% ▮▮▮▮
— 7 days ±7% ▮▮▮
— 14 days ±4% ▮▮
— 28 days ±2% ▮

Weekend CPMs dip, Mondays spike, one whale buyer can move a small site 15% for a day. Reacting to daily RPM is how owners 'optimize' themselves backward.

So what: never judge an ad-layout change on less than 2 weeks, ideally A/B split not before/after. ▼ -19% false signal on day-1 reads.