The Interactive Advertising Bureau has released a new Cross-Channel Measurement Decision Guide for public comment, the latest step in its Project Eidos effort to give marketers a trusted framework for proving what their media spending actually delivers.
The guide, developed as part of Project Eidos, helps marketers use cross-channel measurement evidence to make better-informed investment and optimisation decisions. Public comment is open through November 4, 2026, according to reports.
When the numbers disagree
The guide tackles a problem every media team knows: marketing mix modelling, incrementality testing and attribution can each tell a different story about the same campaign. Rather than asking marketers to pick a winner among the methods, it offers a decision-first approach that starts with the business decision at hand and works backward to the evidence best suited to inform it, according to reports.
“Measurement only works if the industry trusts the answers it produces, and right now, MMM, incrementality, and attribution can each tell a different story about the same campaign,” said David Cohen, CEO of IAB. “This guide gives them a disciplined way to work through the question at hand and make a decision they can stand behind.”
Three connected parts
The guide has three parts: the Decision Guide, which lays out the sequence from business outcome to decision, measurement question, approach, evidence, interpretation and action; the Decision Navigator, which applies that sequence to common choices like allocating budget across channels; and the Measurement Reference Library, which brings together metric definitions and supporting context, according to reports.
Project Eidos is IAB’s unifying initiative for all its measurement work, spanning outcomes, attribution, incrementality, marketing mix modelling, and emerging channels like creator-led media, gaming and retail media.
The timing matters. Marketing leaders report record scrutiny of return on investment from boards and finance committees, with confidence in underlying attribution data far below confidence in overall business strategy, according to industry research. When marketing cannot verify its numbers, budgets get reclassified from revenue drivers to expendable costs, a risk this guide is designed to help the industry confront.
