As CPGs strategize for 2026, retail media is sure to be a cornerstone of their marketing strategy. According to Nielsen's 7th Annual Marketing Report released in May 2025, 65% said that retail media played a growing role in 2025, and its influence will only accelerate. But with billions of dollars spent, brands can’t always pinpoint what’s actually working.

At a time when every dollar counts, CPGs are feeling intense pressure to prove performance. And while marketers are drowning in attribution data from clicks to views, they are still left wondering which advertising generated real impact. More pointedly, the question is: Would that sale have happened anyway?

From correlation to causation

Incrementality—the ability to show which sales were directly caused by media—is now the new standard for accountability. It’s about moving from “this person saw my ad and bought this product” to “this person bought the product because they saw my ad.”

Incrementality provides that proof by measuring sales that wouldn’t have happened without media exposure, which isolates the true impact of advertising dollars. “We believe that incrementality is no longer a report card, but a roadmap for growth," says Shawn McGahee, Sr. Director, Roundel Performance & Insights. “It should be a full framework for measurement—flexible, transparent and designed to prove what really moves the needle.”

This shift is reshaping how brands plan, test and optimize retail media investments. However, many brands are leaving significant performance insights on the table: A report from eMarketer and TransUnion found only about half of brand and agency marketers use incrementality testing to measure their campaigns.

The new incrementality toolkit

Part of the hesitation may stem from outdated perceptions of what incrementality requires. With new methodologies allowing more accurate incrementality measurement, these are three of the functionalities CPGs should prioritize:

• Geo-holdouts: Show ads in some markets while pausing them in similar areas (the “holdouts”), then compare sales to find the true lift.
• Synthetic control models: Use data modeling to create a statistical twin that predicts what would have happened without the ads, comparing the gap between this prediction and actual sales numbers.
• Platform-level Randomized Controlled Trials (RCTs): Split audiences into test and control groups, then compare sales between those who saw the ad and those who didn’t.

Roundel not only exemplifies this multi-method approach but acts as a consultative partner in helping clients measure and interpret incrementality, explains Shawn McGahee, Sr. Director, Roundel Performance & Insights. “While we’ve built out a valuable toolkit for our clients to choose from, we augment that with our sophisticated team who can advise clients on which tools are the best fit for a specific campaign and then interpret key learnings and results to maximize campaign success.”

The four pillars of modern incrementality

As the industry matures, four core qualities define credible measurement:

• Multi-Method Flexibility: Different campaign types require different strategies. A fast brand awareness test might use synthetic control for always-on results on select channels; RCT for single-platform testing; and matched market testing for comprehensive and highly rigorous experiments.
• Comprehensive Coverage: Measurement must capture the entire customer journey across all channels, as digital clicks tell an incomplete story.
• Scientific Rigor: Statistical validity is essential for quantifying results. That means confidence scoring, geo correlation thresholds and in-depth analysis to ensure tests actually detect meaningful lift.
• Transparency: Networks should show their work, with clear methodologies, confidence scores and visual comparisons of test versus control groups for results that are trustworthy and actionable.

Roundel builds on these principles across its measurement framework, providing confidence scoring; 95%+ geo correlation thresholds; and comprehensive omnichannel tracking.

The path forward

The most significant shift isn't just how incrementality is measured, but when. What was once a post-campaign retrospective is becoming a real-time optimization engine, with weekly reads and mid-flight insights allowing marketers to make data-driven decisions while campaigns are still running.

But the real transformation requires collaboration around clear standards—such as established definitions of lift, incremental sales and iROAS—so brands can compare performance across networks with confidence.

Incrementality has become the currency of trust, and networks that embrace flexible measurement frameworks and share their methodologies openly will set the stage for accountable growth.

“Roundel’s continued innovation in matched-market testing, platform RCTs and thorough reporting illustrates where the industry is headed—toward a future where brands can justify every budget decision and optimization happens in real time,” says Shawn McGahee, Sr. Director, Roundel Performance & Insights.

Are you ready to prove what’s really driving your retail media sales? Visit Roundel.com to learn how incrementality measurement can transform your campaigns toward more profitable outcomes.