A retail media campaign concludes with a strong incrementality result. The retailer’s study shows additional sales attributable to the investment. The brand’s analytics team evaluates the impact through a different methodology, while finance looks at revenue, margin and the return required to justify the next investment. None of these perspectives is inherently wrong, but which number should ultimately inform the next budget decision?
That question is becoming more consequential as retail media investment grows. US advertisers spent $60.32 billion on retail media in 2025, with spending forecast to reach $71.09 billion in 2026. At the same time, 67% of CMOs plan to increase their Retail Media Network investment this year, while only 53% believe their RMNs provide adequate measurement and attribution capabilities. As incrementality moves from campaign reporting into larger investment decisions, brands and retailers need greater clarity around what is being measured, how it is validated and, crucially, who owns the number used to make the decision.
The Harder Question Is Proof
The principle behind incrementality is relatively straightforward: determine what happened because of the marketing investment that would not otherwise have occurred.
Putting that principle into practice is more complex.
In Skai and Stratably’s 2026 study of 166 retail media advertisers, 75% identified incrementality as a measurement challenge, ahead of cross-channel measurement at 59%. Yet only 15% said their organisations were very or extremely effective at measuring retail media performance.
The industry itself recognises that gap. At IAB Europe’s 2025 Retail Media Impact Summit, 60% of participants agreed that while incrementality is a worthwhile goal, practical constraints can make it difficult to achieve.
The challenge, then, is not agreeing that incremental impact matters. It is establishing evidence with enough confidence and consistency to guide a commercial decision.
And that brings ownership into the conversation.
Who Owns the Number When the Retailer Owns the Data?
One of retail media’s greatest advantages is its proximity to commerce.
Retailers can connect media exposure with shopper behaviour and transaction data in ways few other media environments can. That gives retailer-led measurement an important role in helping brands understand what happened within that ecosystem.
As investment grows, however, brands may need the same result to answer a broader set of questions. Should more budget move into this RMN? How does its incremental return compare with another network? Did the campaign create additional demand or capture demand already present? What contribution did it make to the wider business?
Answering those questions requires clarity around how the incrementality number was constructed.
Brands need to understand the control group, measurement window and methodology behind the result, alongside the commercial conditions surrounding the campaign. The objective is not to second-guess retailer measurement, but to ensure that the evidence is appropriate for the decision being made.
This distinction matters because not every decision requires the same standard of proof. Campaign optimisation, cross-network comparison and annual budget allocation are different decisions. The measurement supporting them should reflect that.
Incrementality Is a Cross-Business Decision
Retail media does not operate independently of the wider commercial environment. Price changes, promotions, distribution, availability and competitor activity can all influence the same sales outcome that the media is attempting to measure.
NIQ argues that credible incrementality measurement therefore requires visibility beyond media exposure into factors including price, promotions, paid and organic rank, ratings and reviews, buy-box ownership and retail distribution. For example, if distribution expands significantly during a measurement period, the resulting sales lift needs to be understood alongside that change rather than attributed to media in isolation.
This is also why incrementality cannot sit entirely within one function. Media may focus on incremental ROAS, sales on retailer and category performance, ecommerce on conversion, and finance on revenue, margin and profitability. Analytics, meanwhile, brings the methodological lens needed to assess confidence in the result.
Each perspective answers a legitimate question. The opportunity is to agree which outcome matters for the decision being made before measurement begins. Skai’s 2026 research found that only 20% of brands were proficient at both measuring incrementality and applying those insights to decisions, highlighting the importance of connecting measurement with the teams ultimately responsible for acting on it.
Ownership, then, should not simply mean ownership of the calculation. It should mean ownership of the decision the calculation is intended to inform.
Four Questions to Assess Your Incrementality Approach
Rather than asking whether a brand “does incrementality,” a more useful question is how effectively incrementality informs decision-making. Four questions can help marketers assess where their current approach stands.
Are we primarily reporting performance?
Attributed sales and retailer-reported results provide an important view of what happened. The next step is understanding how much of that outcome was generated specifically by the investment.
Are we testing for incremental impact?
Lift studies and other causal approaches can help establish what additional value the activity created beyond what may have occurred anyway.
Are we validating results against wider commercial factors?
Incrementality becomes more useful when results are interpreted alongside variables such as promotions, pricing, availability and distribution that may also influence sales.
Are the findings actually changing investment decisions?
This is ultimately where incrementality creates the greatest value. Insights should inform future planning, retailer allocation and budget decisions, with media, sales, finance and analytics aligned on how the evidence will be used.
The Number Needs Context. The Decision Needs Alignment.
Incrementality becomes valuable at the moment it changes a decision. The real measure of progress, then, is not how many studies a brand can run, but how effectively the evidence informs where investment goes next.
The incrementality number does not need a single owner. It needs a shared standard for when the business is prepared to act on it.
