How to Use Incrementality Testing to Measure Campaign Effectiveness
Imagine your marketing campaigns as the lights at a party—sure, the room might still be lively without them, but would it have the same energy?
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That’s the question incrementality testing answers. It helps you figure out which of your marketing efforts are truly turning up the volume and which are just background noise.
Let’s explore what incrementality testing is, why it’s essential, and how to use it to optimise your campaigns.
What is Incrementality Testing?
Incrementality testing is like putting your campaigns through a dress rehearsal. You take two groups: one that sees your ads (the test group) and one that doesn’t (the control group). By comparing the two, you can pinpoint whether your ads are driving results or simply riding the wave of existing demand.
Why Incrementality Testing is a Game-Changer
- Separate the Star Players from the Extras
Incrementality testing helps you identify which campaigns or channels are actually boosting your conversions, cutting through any noise. - Optimise Your Marketing Budget
By focusing only on the channels that add real value, you can maximise your ROI and avoid wasting money on low-impact efforts. - Data-Driven Confidence
With clear, actionable insights, incrementality testing lets you make smarter marketing decisions based on evidence, not assumptions.
Different Types of Incrementality Tests
- Ad-Level Testing
- Test the impact of different ad creatives, formats, or messages.
- Example: Compare the performance of video ads versus static images to see which drives more incremental conversions.
- Best for: Optimising creative strategies and identifying winning ad formats.
- Channel-Level Testing
- Measure the incremental lift provided by different platforms (e.g., Meta, Google, TikTok).
- Example: Run a holdout test to determine whether your Google Ads are driving unique traffic or just duplicating Meta’s reach.
- Best for: Budget allocation and understanding channel synergy.
- Audience-Level Testing
- Test how different audience segments respond to your ads.
- Example: Compare the impact of ads on cold audiences (prospects) versus warm audiences (retargeting).
- Best for: Fine-tuning your audience targeting strategy.
- Website-Level Testing (Landing Pages)
- Test how different landing pages affect conversions.
- Example: Split traffic between two landing pages with different designs or CTAs to see which drives higher incremental revenue.
- Best for: Optimising the user journey and improving website performance.
- Full-Funnel Testing
- Analyse the cumulative impact of touchpoints across the entire customer journey.
- Example: Test how a combination of awareness, consideration, and conversion campaigns contributes to incremental sales.
- Best for: Understanding how upper- and mid-funnel activities impact lower-funnel results.
Key Metrics to Watch
- Incremental Lift
The percentage increase in conversions directly attributed to your ads. - Incremental Revenue
How much additional revenue your ads bring in compared to what would’ve been earned without them. - Return on Ad Spend (ROAS)
A clear measure of the revenue generated for every pound spent on your campaigns.
Challenges and How to Overcome Them
- Audience Overlap
If your test and control groups overlap, your results could be compromised. Use tools like Meta’s split testing feature to keep them separate. - Small Sample Sizes
Incrementality tests need a solid number of participants to produce reliable insights. For smaller audiences, run the test over a longer period. - External Influences
Holiday sales or sudden events can skew your data. Choose your testing windows carefully to avoid these confounding factors.
Tools to Simplify Incrementality Testing
- Google Ads Experiments
Provides built-in capabilities for split testing and measuring lift at various levels, from ad creatives to landing pages. - Meta Experiments
Allows holdout testing to measure the true incremental impact of your campaigns on Facebook and Instagram. - SplitMetrics
A go-to tool for app marketers looking to measure incremental installs or purchases.
Conclusion
Incrementality testing is like running a soundcheck before the big performance—it ensures every campaign is hitting the right notes and truly adding value. But don’t stop there.
Combine it with Multi-Channel Attribution to see how all your efforts come together and use First-Party Data Strategies to build a reliable foundation for measurement. Together, these tactics will give you the ultimate toolkit for optimising your marketing strategy.
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