What is cannibalisation in marketing?
How does cannibalisation show up?
Take the brand search case. Someone types your brand name. Your ad appears above your organic listing. They click the ad and buy. The ad gets the credit and the cost. The organic click that was coming anyway gets nothing.
The report looks excellent. ROAS on brand search can look very high, because these shoppers were already on their way. The question is what the ad added.
Cannibalisation is not only about brand search. Any two campaigns, channels or offers can overlap and credit the same customer twice.
Is brand search always cannibalising?
No, and the evidence points both ways. A series of large field experiments at eBay, by Blake, Nosko and Tadelis (Econometrica, 2015), found that brand keyword ads had no measurable short-term benefits2. The authors call it an extreme case. That is one company in one period. It does not describe your brand.
In the other direction, a paid media agency paused brand bidding for one unnamed client in 2021. It reported higher combined traffic, sign-ups and purchases with paid and organic running together than with organic alone, and recommends bidding on brand terms3. That is an agency describing its own work for one client, which had no competitors bidding on its brand.
Two results, two directions. Neither is yours. The only way to know is a controlled comparison, such as a holdout test.
Our view: judge overlapping activity by total sales and margin, not by what each platform credits to itself.
Worked example
Easily confused with
Cannibalisation vs Incrementality
The extra sales caused by an activity, over and above what would have happened without it. Cannibalisation is the shortfall: credit for sales that were not extra.
Cannibalisation vs Product cannibalisation
A different meaning: a new product taking sales from one you already sell.
Cannibalisation vs Impression share
In Google Ads, the share of impressions your ads received out of the total they were eligible for. A coverage figure, not proof of added sales.
FAQ
Does branded search cannibalise organic traffic?
How do I test for cannibalisation?
Hold the activity back in a controlled way and watch total sales, not platform-reported sales. The holdout test entry explains the idea.
What is "brand tax"?
An industry phrase for branded search spend that captures demand you would have received organically, as one Google Ads agency's glossary defines it1. It is cannibalisation with a sharper name.
Is cannibalisation the same as incrementality?
No. Incrementality is the extra sales an activity caused. Cannibalisation is what is left when credit goes to sales that would have happened anyway.
Let’s find what’s actually working.
Next step. Start with what platform ROAS credits versus what it costs you. Use the Is your ROAS real? calculator.