I want to walk through something deceptively simple that trips up smart people c
By Michael Erickson Facchin · August 9, 2026 · Curated by George's Blog
I want to walk through something deceptively simple that trips up smart people constantly: 1 click on 100 impressions is a 1% CTR. 2 clicks on 100 impressions is 2%. 3 clicks is 3%.
On paper, that looks like a clean, steady trend, CTR tripled! Something's working!
Here's the problem: at 100 impressions, one extra click is the entire difference between those numbers. That's not a trend, that's noise wearing a trend's clothing. The sample size is so small that a single person having a good day is statistically indistinguishable from a genuine shift in ad performance.
I see this mistake constantly, at every level of experience: someone sees a keyword or a placement move from 1% to 3% CTR and reports it as a finding, a "this creative variant is winning," a "let's shift budget here" decision , off of three total clicks.
Before you act on any CTR, CVR, or ACoS change, ask the only question that actually matters: how many impressions, clicks, or orders is this number built on? A CTR change based on 50,000 impressions and a CTR change based on 100 impressions can look identical on a dashboard and mean completely different things.
This is the unglamorous, unsexy part of Amazon advertising that separates people who make decisions from data and people who make decisions from noise that happens to look like data. Statistical significance isn't a nice-to-have concept from a stats class. It's the difference between a real optimization and reorganizing your account based on what three random shoppers did on a Tuesday.
Check your sample size before you trust your trend line. Every time.