❓Why does Google Analytics 4 report 2-10x higher ROAS for branded search, compared to Marketing Mix Modeling -reported ROI?
Here’s what often happens in a buying journey:
1. A person wants to buy something from an online store.
2. The person opens Google and searches for the name of the online store.
3. The first item in search results is a search ad of the online store.
4. The person clicks the search ad and proceeds to buy the desired product(s).
What Google Analytics 4 (GA4) sees: Lots of conversions originated from people clicking the branded search ad.
What GA4 does not see:
💡 Many buyers taking the journey above would have ended buying the product anyway, even without the branded search ad.
💡 Some buyers taking the journey above were triggered to buy already well before seeing the search ad. They might have seen a TV ad, an out-of-home ad, a display banner, a social media campaign etc.
So, why is Marketing Mix Modeling (MMM) -reported ROI so much smaller compared to GA4-reported ROAS?
👉 MMM estimates the true incrementality of branded search ads. Conversions which would have happened in any case, are included in ”base sales”, not in "sales-driven by branded search ads".
👉 MMM estimates the fair contribution that the other media had earlier in the buying journey.