CRO Glossary
North Star Metric
The single metric a team optimizes above all others because it best captures long-term value delivered to users and the business.
A North Star metric is the one number an experimentation program rallies around when a test moves several metrics in different directions. It should represent genuine long-term value, not just an easy-to-move proxy — for example, 'weekly active users completing a core action' rather than raw signups, since signups alone can be inflated without real engagement.
North Star metrics matter in CRO because tests very often show tradeoffs: a more aggressive urgency banner might lift immediate conversions but hurt trust and long-term retention. Having an agreed North Star, backed by supporting guardrail metrics, gives teams a tiebreaker rule instead of relitigating priorities on every experiment readout.
For an e-commerce company, the North Star might be repeat purchase rate rather than single-session conversion rate; for a SaaS product, it might be activated accounts reaching a usage threshold rather than raw trial signups. The key discipline is resisting the urge to change the North Star every quarter just because a test doesn't move it favorably.
Related terms
Above vs Below Median Split
A segmentation technique that divides users into two groups at the median of a metric to compare high and low engagers.
Qualitative Feedback Loop
A recurring process of collecting and acting on user comments, session recordings, and survey responses to inform test hypotheses.
Experiment Metadata
The structured record of who, what, when, and how for a test — hypothesis, owner, dates, variants, and metrics used to track and audit it.
Pre-Test Analysis
The upfront work of validating traffic, metrics, and baseline data quality before launching an experiment.
Above-the-Fold vs Below-the-Fold Messaging Hierarchy
How the order and prominence of value-proposition messaging is split between the visible screen and the rest of the page.
Experiment Contamination
When a control or variant group is unintentionally exposed to the other condition, corrupting the comparison.
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