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Google's Privacy Sandbox enters testing


Simon Harris 22 nov. 2023

Into uncharted territory: Google's Privacy Sandbox enters testing

In 2019 Google announced the Privacy Sandbox. In H2 2024 Google will deprecate third party cookies in Chrome and launch it at last. 

This is a meaningful moment for the online advertising ecosystem as Chrome accounts for 55% of browser usage in the Netherlands & 57% in Belgium. Third party cookies will be replaced in Chrome by a suite of APIs which Google calls the Privacy Sandbox, of interest to advertisers and publishers are what Google calls the Relevance & Measurement (R&M) APIs, namely:

  • Topics - A proposal that creates interest based audiences within the Chrome browser that can be targeted by AdTech.
  • The Protected Audience API (PA-API) A proposal that supports remarketing and niche audiences that can be targeted by AdTech.
  • Attribution reporting API (ARA) A proposal that allows campaign effectiveness to be measured by AdTech. 

People often think of the Privacy Sandbox as something that is constantly changing but the R&M APIs are now available in Chrome 115 and are not expected to change significantly. Most of the key AdTech companies in the ecosystem are now preparing for testing early next year. 

What Does Testing Look Like? 

Google will begin deprecating third party cookies in Q1 for a small percentage of Chrome users. They call this testing Mode B testing and it is designed to understand whether or not the Privacy Sandbox tools are effective replacements for third party cookies both for publishers and advertisers.

Within Mode B Google plans to provide a small fraction of traffic within Mode B that has three key R&M APIs disabled. The rationale for this is to establish a baseline of performance without third-party cookies or the Privacy Sandbox R&M APIs.

All testing will be overseen by the UK Competition & Markets Authority (CMA for short). The CMA will try to ensure solutions are fair and effective for both advertisers and publishers with success will be judged through the analysis of a variety of metrics, a full list can be found here.

The CMA will be analysing data from these tests in Q2 of 2024. Assuming the tests show no significant impacts for buyers and sellers the plan is to commence the deprecation of cookies the following quarter (Q3 of 2024). 

There are concerns however that the AdTech systems that publishers use might not have the ability to provide publishers with the information they need to assess whether or not these new APIs perform as expected. 

Particularly there are concerns that basic information on whether a user falls into a test group or not and whether the APIs are present will not be immediately accessible to publishers in their ad-server. This notable absence will make passing feedback to the CMA, both good and bad, very difficult. 

Whilst DPG Media’s Trusted web strategy means that we are much less reliant on these initiatives than many other publishing groups, we hope that Google hears the concerns from the ecosystem and does as much as possible to make these trials easy for all to participate in, regardless of their resources. Ultimately this is in the interests of all stakeholders in an open and ad funded internet.

Simon Harris
Programmatic trading expert

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