Taylor said on a briefing call with reporters this week that not testing Topics API in isolation was intentional.

“We did this because the Topics API is not being designed as a standalone offering,” he said.

The experiment also only tested a set of privacy-preserving targeting protocols and not other current use cases for cookies, like remarketing and attribution, which Privacy Sandbox protocols Fledge and Attribution API aim to respectively solve.

“We definitely want to be able to see how the other APIs perform both in isolation and then as a total package,” Taylor said on the call, on the choice to not test Fledge or Attribution API.

Finally, the test showed that the IBA traffic produced better results for advertisers when they also used some of Google’s AI-driven ad-buying tools. Machine learning has been advantageous in filling gaps amid signal loss.

But what is unknown is how buyers using other demand-side platforms outside of Google’s ad-tech tools might replicate those results.

“Other companies provide their own solutions in this space …. based on their own proprietary technology,” Taylor said. “Google built solutions that are focused on leveraging Google’s AI to deliver results.”