Measurement guide
Affiliate Marketing Incrementality
Incrementality asks a harder question than attribution: did the affiliate or partner create additional commercial value, or would the customer probably have converted anyway?
Why last click is not enough
Affiliate platforms commonly report attributed conversions, but attribution alone does not prove causality. Brands can examine new-customer contribution, first-touch involvement, customer journeys, partner type, code leakage, holdout or ghost tests where feasible, and changes in kept revenue or acquisition cost.
Questions to ask an agency
Ask how it evaluates publisher quality, whether commission reflects incremental contribution, how it treats voucher and lower-funnel partners, what customer-level data it can use, and how findings change optimisation decisions.
Transparency matters
A strong reporting model should make it possible to understand which partners are driving demand, assisting discovery or capturing demand near conversion, rather than treating every tracked sale as equivalent.