Does SEO cannibalize SEA?

Does SEO cannibalize SEA? Is there a real business case for boosting your SEO ranking?

Here’s how to find out:

❌ NOT by blindly analyzing raw Google Analytics or MMM data.
✅ BUT by pausing Google Search Ads in certain regions while keeping them active in others.

This method is called a regional incrementality test, and it helps establish a baseline by showing the real conversions without Google Search Ads.

The difference between this baseline and your actual conversions? That’s the incremental impact of your ads.

Here’s the key:
Split your conversions into two groups:
🔹 Products with high SEO rankings
🔹 Products with low SEO rankings

The result:
For products that already rank high in SEO, the incremental effect of SEA is likely to be lower. Customers would have found your site organically anyway. However, for products with low SEO rankings, the incremental effect will be higher. Customers might turn to competitors or alternative options.

In other words, SEA cannibalizes more on well-ranking SEO pages.

Why does this matter?
🔹The better your SEO, the less you need to spend on paid ads.
🔹The difference between your cost per incremental conversion and the cost of improving your SEO is your business case for investing in SEO.

Now, the real question is: how much budget are you still wasting on SEA, where SEO could have done the job?