Thursday, June 4th, 2026 – 12:35 am
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The W3C’s proposed “Attribution Level 1” browser standard deserves far more scrutiny from the advertising and measurement community than it has so far received. The public comment period remains open through June 10.
At a moment when advertisers face enormous pressure to justify spending and many publishers outside the largest platforms are struggling economically, industry standards bodies should be encouraging more rigorous causal measurement, not reinforcing decades of confusion between observational attribution and advertising effectiveness.
The proposal is framed primarily as a privacy-preserving replacement for older forms of cross-site tracking and attribution in a post-cookie environment. But embedded within the specification is a much larger and more consequential assumption: that attribution systems are valid mechanisms for determining advertising effectiveness.
