In short: In media planning, affinity expresses how much more strongly a medium or programme reaches a chosen target group than the population as a whole.
How I use affinity in practice
Before tracking affinity, I write its precise definition, data source and decision it should influence. I check numerator, denominator, time window, currency and duplicates. I read the value in the context of margin, capacity and customer quality; one number without comparison cannot tell a company what to change.
What to watch
The greatest risk is a report without a decision. If affinity is measured merely because the interface offers it, the team gets another graph, not better management. Beware comparing periods in which the website, tagging or counting method changed.
Questions for decisions
- Exactly how do we calculate the value and from which source?
- Which decision changes when the number rises or falls?
- What can distort or duplicate measurement?
- What do we compare the value with so it has business meaning?