Where it is used
- Partnership selection. High overlap with a property means the audience is already there: easy to activate, limited in new reach.
- Additional reach. Low overlap with high affinity is often the better buy. The audience fits, and little of it is yours today.
- Competitive analysis. Overlap with a competitor shows how contested an audience is, and which parts are not.
The formula
Overlap is not symmetric
This property is often misread. If 60% of a small audience also belongs to a large one, it does not follow that 60% of the large audience belongs to the small one.
Overlap and affinity answer different questions
- Overlap is about people: how many individuals are shared.
- Affinity is about lean: how much more than average one audience engages with something.
Two audiences can have high affinity and low overlap: similar in character, barely intersecting in practice. For expansion, that combination is often the one worth looking for.
Common mistakes
- Quoting one direction only. Both directions are correct and support opposite conclusions. A report must say which one it quotes. A partnership case built on the flattering direction will not survive the first question from finance.
- Confusing overlap with fit. High overlap says the people are shared, not that the partnership will add anything.
- Mixing markets. Overlap in one country says little about another. Compare within the same market.
How Rascasse uses it
Rascasse compares audiences from aggregated, non-personal behaviour signals rather than matched personal identifiers, so no personal data is processed and no CRM data is needed. Comparisons are made within one country at a time. This is what drives partner shortlists in sponsorship and brand partnership work.
Related use cases: Sponsorship Matching & Pitch, Brand Partnerships & Co-Branding, Competitive Intelligence.