CRO Glossary
Social Proof
A persuasion technique showing that other people have chosen, used, or approved of something, to reduce a visitor's perceived risk.
Social proof leverages the psychological tendency to look to others' behavior when we're uncertain about a decision. On a website this shows up as customer counts ("Join 40,000 subscribers"), star ratings, testimonials, recent purchase notifications ("Someone in Ohio just bought this"), trust badges, or logos of well-known customers. The underlying mechanism is reducing perceived risk: if many others have already made this choice safely, a new visitor infers it's probably safe for them too.
It's one of the most consistently tested CRO tactics because it's cheap to implement and often produces measurable lifts on product and checkout pages, particularly for unfamiliar brands or higher-consideration purchases where risk perception is the main barrier. That said, effectiveness depends heavily on credibility and relevance — a vague "trusted by thousands" claim moves the needle far less than a specific, verifiable number or a testimonial from a relevant peer group.
Social proof interacts closely with urgency tactics (e.g., "12 people are viewing this right now") and should be tested with a guardrail metric on trust-related signals, since overly aggressive or fake-looking social proof (constantly popping "X just bought this" notifications) can backfire and erode credibility if it feels manipulative.
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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