Why Strategic Incrementality Testing is Critical for Success

The Illusion of Control

Let’s be honest, automation has been a game-changer in the performance marketing industry. Tools like Google’s Performance Max, as one of the first most significant AI advances in this industry, and Meta’s Advantage+ have taken the heavy lifting out of campaign building and management, allowing brands to operate at a speed and scale that was impossible 5 years ago. 

However, as a leading expert in the performance marketing industry, we also know that automation comes with a cost. As platforms move towards AI learning and take over the day-in-day-out control of campaign management, we lose visibility on what’s going on underneath the bonnet, swapping our manual levers for algorithmic “black boxes”. 

For those who have to decide where to invest their marketing budget, this creates a new challenge. The platform may say your campaigns are winning, but does that align with your bottom line? In an era where marketing budgets are being scrutinised like never before, with a close lens on efficiency, we need to focus on understanding whether our campaign drove new revenue, ultimately increasing our bottom line.

This is how the best marketers, or agencies, separate themselves from the pack. It’s not about fighting the algorithms, it’s about auditing them to work in tandem in the most effective way possible.

The Black Box problem

Algorithms are ultimately designed to be efficient, not necessarily strategic. Their goal is to get you the next conversion at the lowest possible cost. That is the reality of the modern “Black Box”.

It’s essential we put strict guardrails in place to ensure the algorithms don’t just take the path of least resistance, and instead prioritise effective targeting to bring in new customers and incremental revenue. A great example of this in practice is the reality that without controls in place, PMax will likely prioritise capturing brand searches, essentially targeting your engaged and loyal customers. 

At Summit, we work with multiple retailers that have significant brand equity, and it’s essential that we protect paid media budget to ensure it’s prioritised for non-brand and discovery-based terms, rather than targeting brand activity that isn’t likely to drive incremental gain. Through testing, we found the right restrictions to put in place for each of our partners, ensuring they have the best coverage, without compromising on efficiency.

Understanding the incrementality

In a world where automated platforms optimise towards the cheapest, fastest conversion, incrementality becomes the truth behind the performance. It moves away from vanity metrics and towards understanding what truly adds value.

Incrementality is the measure of what your marketing activity actually caused (the revenue that would not have happened without the campaign). That’s why shifting focus from standard ROAS to iROAS (incremental Return on Ad Spend) is crucial. iROAS forces us to quantify whether our spend drove profitable growth rather than simply capitalising on demand that already existed.

When we evaluate paid activity through an incrementality lens, it is clear what channel, campaign, or audience is genuinely contributing to growth, which then ensures budget is being invested where it drives real uplift, rather than algorithms taking credit for conversions they didn’t earn.

Continuous testing drives success

Algorithms evolve, consumer behaviour changes, and competitive landscapes shift daily, that’s why continuous testing is so important to pressure-test platform assumptions, expose inefficiencies, and identify opportunities that automation alone may not uncover.

This means building a structured testing framework around audiences, creative, bidding structures and more. Testing should be a constant strategic tool, not a reactive exercise. When executed consistently, it strengthens the relationship between human expertise and machine learning, ensuring campaigns stay both efficient and strategically aligned with campaign and channel goals.

Summary

Automation continues to reshape the performance marketing landscape and although it’s tempting to rely on algorithmic black boxes and the illusion of control, applying clear guardrails, auditing systems and rigorous testing is key to stay ahead and to ensure every pound spent drives true, incremental growth.

At Summit, we’re committed to helping our partners navigate this evolving landscape with clarity and confidence. If you’re looking to work with a Premier Partner who truly understands the retail environment, reach out to our team today.