SYS/DEF
CVR
Conversion rate: conversions divided by the denominator you chose (sessions, users, clicks).
Definition
CVR is a ratio: conversions / population size. The population is not free: sessions, unique users, ad clicks. A 2.4% session CVR and a 3.1% user CVR can describe the same site. Writing “the conversion rate” with no denominator is talking in order to say nothing.
It is a binary metric at unit level: each unit converts or not. That is why proportion tests (z, binary MDE) apply, and the continuous AOV formula does not.
When it matters
Everywhere: sizing, significance, lift, traffic for a revenue goal (sessions = revenue / (CVR × AOV)). It is also the bridge between SEO/SEA and CRO: a Quality Score or a ranking that sends unqualified traffic drops CVR without the page getting worse.
For a test, the baseline CVR must be measured on the same unit, window, and device split as the future experiment.
Pitfalls
Switching from session to user mid-quarter to “improve” the rate. Including internal traffic. Computing CVR only on visitors who saw the thank-you pixel. Reporting a +20% relative lift on a 0.4% CVR without saying that is +0.08 points — and without a CI.
Related terms
Related tool
Turn a revenue goal into sessions via CVR and average order value: Open traffic for a revenue goal.