Published on December 12, 2023
Background
As part of Google's commitments to the UK Competition and Markets Authority (CMA), Google’s ads platforms, including AdSense, are working under the supervision of the CMA to design and conduct experiments to evaluate the effectiveness of the Privacy Sandbox APIs and other privacy-preserving signals supporting key online advertising use cases without third-party cookies.
As part of Chrome-facilitated testing, Chrome is providing two testing modes that allow sites to preview how site behavior and functionality works without third-party cookies.
- Mode A: In Q4 2023, AdTech providers testing Privacy Sandbox can opt in to receive consistent labels on a subset of Chrome browsers. AdSense has been actively testing in this mode.
- Mode B: In Q1 2024, Chrome will globally disable third-party cookies on 1% of Chrome traffic. Using Mode B, AdSense will be running a test to evaluate the impact of third-party cookie deprecation and will be reporting results to the CMA in Q2 2024.
Both modes will continue through to at least Q2 2024. Also, when third-party cookies are disabled in Mode B (for 1% of Chrome traffic), they will remain disabled through the full phase out of third-party cookies.
The primary goal of Mode B testing is to quantitatively understand the impact of third-party cookie deprecation, and the effectiveness of the Privacy Sandbox technologies.
Testing design
In the Mode B test set up, traffic is divided into three groups, as recommended by the CMA.
- Control 1: Status quo baseline (with third-party cookies where available)
- Control 2: No third-party cookies, without Privacy Sandbox APIs, with other mitigations such as publisher first-party cookies for personalization
- Treatment: No third-party cookies with the Privacy Sandbox APIs, with other mitigations such as publisher first-party cookies for personalization.
What should be expected from the testing results?
The test will help us evaluate the effectiveness of the Privacy Sandbox relevance APIs, and share our findings with the UK’s Competition and Markets Authority, Chrome, and the industry. We anticipate that the results of this test will be shared with the CMA in April 2024.
We expect the results from this testing to be an early indicator of the expected performance without third-party cookies. We would consider this a baseline, since we expect the performance to improve with increased adoption, optimization, and coverage for Privacy Sandbox and other privacy-centric technologies to improve as the ecosystem prepares for third-party cookie deprecation.
Is there any publisher action needed as part of this testing?
No publisher action is needed as part of this testing. AdSense is working directly with Chrome, participating SSPs and DSPs, and the CMA to conduct the test.
Can publishers opt out of this testing?
Publishers have the ability to opt out of the Protected Audience or Topics API using Chrome’s Permissions-Policy. However, publishers cannot opt out of Chrome-facilitated testing for advertising use cases.
