How to Add Incrementality Testing to Your Marketing Campaigns
Why measuring true channel impact matters more than ever
Written by: Ashley Ruggeri, Account Director
If there’s one thing most marketers can agree on, it’s this: today’s customer journey is anything but linear. People bounce between channels, tabs, devices, offline experiences, and influences you can’t easily track in a dashboard.
Yet many teams are still measuring success using last-click attribution, which gives 100% of the credit to the final interaction—undervaluing the rest of the marketing ecosystem that actually did the heavy lifting.
The truth is:
Channels work together.
Attribution is messy.
And most reporting only tells part of the story.
That’s where incrementality testing becomes one of the most valuable tools in your measurement strategy.
What Incrementality Testing Actually Tells You
Incrementality testing measures the true lift generated by your marketing—not just the clicks, and not just the people who would have converted anyway.
Instead of relying on directional performance, incrementality gives you causal performance. It’s the difference between: “Email drove 100 sales.” and “Email drove 32 incremental sales we would not have seen otherwise.”
That’s a completely different story—and a far smarter way to allocate spend.
Why Incrementality Matters in a Multi-Touch World
Today’s buyers interact with multiple touchpoints before converting. Search may take credit. Social may get the click. Your website may get the attribution. But maybe Acquisition Email or Connected TV actually triggered the interest that made everything else possible.
Incrementality helps you:
✔ See the bigger picture across the full funnel. Instead of assigning credit to the last touch before conversion.
✔ Understand true budget impact. Not just clicks or impressions—business outcomes.
✔ Make confident investment decisions. Especially when adding new channels or testing new tactics.
✔ Validate your channel mix before scaling. Because a channel that “looks good” in platform dashboards might not actually be driving incremental value.
The Blueprint: How to Run an Incrementality Test
Below is the simplified process—one we use at Blue Duck Agency across campaigns for Acquisition Email, New Movers, digital programs, retention, and more.
1. Define a Clear KPI: Pick one measurable success metric—incremental ROAS, sales lift, revenue per user, etc.
2. Segment Your Audience: Create comparable test and control (otherwise known as holdout) groups that closely mirror each other. Ensure your holdout group is statistically significant.
3. Deliver Marketing to the Test Group Only: This ensures clean measurement without cross-contamination.
4. Measure Lift: Compare performance between groups, otherwise known as incrementality.
5. Interpret + Optimize: Use the results to optimize channel budgets, creatives, messaging, and mix.
This structured approach gives you a defensible, repeatable framework for testing—removing guesswork and giving you the data confidence every marketing team wants.
Ready to Add Incrementality Testing to Your Strategy?
Blue Duck Agency builds tests that are statistically sound, operationally feasible, and aligned to your business goals.
Ready to test a new channel or need help understanding which parts of your current marketing mix are really creating lift? We can help.
Let’s talk. Send me an email at ashley@blueduckagency.com.