Why CMOs Should Stop Chasing ROAS And Start Measuring Impact

Forbes

4 days ago

Liam Wade - Performance Director at Performance Marketing Agency, Impression.
In a competitive landscape, the way you measure performance shapes the way you invest—and that can make or break your growth. If your decisions are based on surface-level metrics like return on ad spend (ROAS), while your competitors are optimizing against true business impact, you're not just at a disadvantage. You're playing a different game entirely.
ROAS has become the go-to metric for many. It's quick, accessible and easy to drop into a slide deck for the boardroom. A high ROAS can boost confidence, justify more budget and make teams feel as if they're winning. However, there's a problem: ROAS rarely tells you what's actually working. It shows correlation, not causation, and that distinction matters.
The companies that win in today's landscape aren't just running ads. They're measuring what those ads really did—not what they touched, but what they changed.
The Problem With ROAS
ROAS is often treated like a bottom-line metric. Spend $1, get $5 back? Sounds good? Here's the catch: It tells you what happened after someone saw or clicked an ad. It doesn't tell you if the ad had anything to do with the outcome.
This becomes a problem when the campaigns showing the highest ROAS, like branded search or remarketing, are often reaching people who were already likely to convert. These campaigns look brilliant, but they're not creating new demand. They're just scooping up what was already there.
To make things worse, ROAS is built on tracking models that rely heavily on cookies and click paths. In theory, they map a clean journey. In practice, they miss most of what's going on—privacy restrictions, ad blockers, dark social and offline activity. You're seeing just a fraction of the picture and assuming it's the whole.
When the same platform runs your ads and tells you how they performed, let's just say they don't have much incentive to be neutral about it.
The Cost Of Optimization Obsession
Over time, this obsession with ROAS creates an even bigger issue. Teams stop asking the big questions. Instead, they focus on squeezing marginal gains out of short-term tactics.
You've probably seen this play out. Endless A/B tests. Bid adjustments. Hyper-specific audience filters. It looks like progress, but it can actually distract from more important questions: Are we bringing in new customers? Are we building a brand people care about?
Worse, chasing ROAS can quietly damage long-term performance. Eventually, the algorithm starts chasing easy wins (existing customers, bottom-funnel conversions), while upper-funnel or experimental campaigns quietly get deprioritized—not because they don't work but because they don't show up in the right column of a dashboard.
It's a pattern I've seen too often, what I call dashboard delusion. Everything looks great, but it's actually at the expense of real growth.
What CMOs Should Measure Instead
Here's the question I always come back to: What would have happened if we hadn't run this campaign?
That's the heart of incrementality. It doesn't ask what an ad touched. It asks what it caused. That's the only way to know whether your marketing is really moving the needle or just riding the wave.
There are a few ways to approach it:
• Run geo tests. Show ads in one region, hold them back in another, and compare.
• Use holdout groups. Suppress campaigns for a random sample and measure the delta.
• Tap into platform lift studies. Meta and Google both offer tools to run controlled tests within their ecosystems.
If you're working across multiple channels, marketing mix modeling (MMM)—or econometrics—can also help. It's slower and, yes, more complex, but it's useful for spotting directional trends and understanding the broader impact when clean tracking isn't possible.
None of these methods are perfect, but they don't need to be. Even directional insight can show you where spend is creating value and where it's not, and that's far more useful than another line on a ROAS report.
Leading The Shift
Measurement should propel, not paralyze. As a CMO, it's your responsibility to champion the mindset behind incrementality—not as a technical exercise but as a leadership stance. That means setting the expectation that your team, agencies and partners look beyond short-term efficiency and bring forward insight that shows causality, not just correlation.
Keep the dashboards—just question what they're really telling you.
Here's what that looks like in practice:
• Treat ROAS as a signal, not a verdict. It can point to patterns, but it shouldn't be your only lens.
• Ask your team for incremental impact. Even rough or directional data is better than chasing false precision.
• Champion a test-and-learn culture. Reward smart questions and open-minded analysis—even when the results sting a little.
• Protect long-term investments. Not everything will show an immediate return. That doesn't mean it's not working. Sometimes, the things that matter most are the hardest to measure.
This isn't about having one perfect metric. It's about building a culture that cares more about truth than theater.
Conclusion
In a competitive market, the way you measure success defines the way you grow. If your team is chasing ROAS and your competitors are measuring what really works, you're falling behind—whether you can see it yet or not.
The shift from attribution to causality isn't a technical upgrade. It's a strategic one. It's about moving from surface-level confidence to real, actionable insight.
By embracing incrementality, CMOs can lead smarter teams, make bolder decisions and build more resilient brands in a world where clarity is harder—and more valuable—than ever.
Ultimately, if you're measuring ROAS and your competitors are measuring incremental impact, you will plateau, stagnate and eventually lose.
Forbes Communications Council is an invitation-only community for executives in successful public relations, media strategy, creative and advertising agencies. Do I qualify?