The data behind incrementality on Amazon
Maximizing sales across category and competitor terms
In terms of incrementality, nothing is better than capturing a sale from your competitor. However, you’re likely to find that the ACoS of competitor keywords is significantly worse than that of generic or category keywords, as shown in the example below.
The best strategy here depends a lot on your competitive landscape. Conquesting your competitor’s terms means having a deep understanding of the terms which you can reasonably bid against successfully. Terms relating to stronger competitors with deeper brand loyalty/recognition may necessitate a less aggressive strategy to control costs, while it may be well worth your while to bid forcefully against terms related to relatively weak competitors where it’s easier to pick off customers with your top products.