Learn · Module detail
understanding incrementality
Incrementality is the behaviour caused by a loyalty intervention beyond what comparable members would have done without it. Estimate it with a credible comparison, then value only the genuinely changed behaviour.
## The mechanism
Define the qualifying event, value change, owner, correction path, and member explanation. Keep eligibility, liability, fulfilment, consent, and reversal as separate rules. The operating control must be testable from the ledger.
## Worked example
Illustrative arithmetic: treatment members generate 90 purchases and comparable holdout members generate 75. The observed difference is 15 purchases, subject to contamination and baseline checks.
## Do it
State the rule in one sentence. Map the event that starts it, the event that changes value, the exception path, and the review action. Test ordinary, cancelled, duplicated, and disputed cases before release.
## Common mistakes
- Measuring activity instead of the target behaviour. Name the counterfactual. - Treating face value as operator cost. Price fulfilment and correction. - Hiding exclusions or expiry. Put the boundary beside the decision. - Automating an undefined rule. Resolve ownership before implementation.