Attribution, incrementality & effectiveness · Working
Spillover
Also called: contamination
ELI5
An effect of an intervention on people, markets or outcomes outside the intended treatment unit.
Used in conversation
“The number is useful only if everyone calculates spillover the same way.”
Pitch context
You will see “Spillover” in brand decks, campaign plans, research reports and performance reviews when the discussion reaches attribution, incrementality & effectiveness.
Why it matters: It helps a reader interpret attribution, incrementality & effectiveness without confusing the measure, decision, role or evidence being discussed.
Sources & evidence · 5
Direct term-level sources and supporting source families.
- Google Analytics Help — Google Analytics dimensions and metricsDirect source · primary · checked 2026-08-16
- Interactive Advertising Bureau — Measurement guidelines and standardsDirect source · institutional · checked 2026-08-16
- American Marketing Association — Definitions of Marketing and BrandSupporting source family · institutional · checked 2026-08-16
- U.S. Federal Trade Commission — Advertising and Marketing GuidanceSupporting source family · primary · checked 2026-08-16
- Google Ads Help — Google Ads metrics and reportingSupporting source family · primary · checked 2026-08-16