The denominator defines the question a rate answers
State which actions and eligible visits are included before comparing conversion rates. A rate based on all sessions is not interchangeable with one based only on campaign landing visits.
A conversion rate can use sessions, visitors, ad clicks or accepted opportunities as its denominator. Those are different populations. Name both the qualifying outcome and the eligible population before comparing percentages.
A worked example
In a hypothetical month, 20 inquiries arise from 1,000 sessions and 800 measured users. The session-based rate is 2%; the user-based rate is 2.5%. Neither is inherently the correct universal rate. Comparing one with another period’s different definition creates an artificial change.
How to apply it
- Write the numerator, denominator, exclusions and period beside the calculation.
- Use a consistent population and distinguish people from repeated events.
- Report absolute counts with the rate so small samples remain apparent.
What the result can establish
Check that a changed rate reflects behavior rather than event duplication or filtering. A form-success rate is not an opportunity close rate. Use the rate aligned with the decision, then retain its definition for future reports.
Reference: Google Analytics: recommended events.
Supporting documentation
Google Analytics: recommended eventsGoogle Analytics: attribution overview