CRO Glossary
Exposure Rate
The percentage of eligible visitors who actually saw a test variant, used to check whether an experiment is running as intended.
Exposure rate tracks how many visitors who were supposed to see a test experience actually received it — a page might fail to load a variant due to caching, ad blockers, JavaScript errors, or targeting bugs. If a test is meant to run for 100% of traffic on a page but only 60% of eligible visitors are logged as exposed, something is likely broken in the implementation.
Low or inconsistent exposure rates are a common, under-diagnosed cause of confusing results, including sample ratio mismatch (SRM). For example, if a test's JavaScript snippet loads slower for the treatment group (because it renders more content), some users may bounce before the exposure event fires, artificially shrinking that group and biasing the comparison.
Before trusting any test result, it's worth checking exposure rate alongside sample size: are roughly the expected number of users landing in each variant, and is that number close to 100% of intended traffic? A big gap is a signal to debug the test setup before interpreting the outcome.
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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