In-store media has a measurement problem, just not the one most people think.
Retail media has no shortage of metrics. The gap is in how few of them connect directly to what happens at the shelf. With IAB forecasting 12.1% growth in commerce media spend for 2026, the stakes around getting in-store measurement right have never been higher. Brands, retailers, agencies, and RMNs each evaluate in-store success through entirely different scorecards, and that misalignment, not a lack of proof points, is what stalls investment at the planning table.
To fix it, ISM developed Shopper Purchase Rate (SPR), a new measurement framework built around the question every stakeholder cares about: Did the product sell? SPR gives retail stakeholders a shared foundation for evaluating in-store performance without forcing physical stores to behave like digital channels.
What Is SPR?
Shopper Purchase Rate (SPR) is a measurement framework developed by ISM to give brands, merchants, agencies, and RMNs a common language for evaluating in-store media performance. “Rate” signals a standardized, repeatable measure, the kind every stakeholder can anchor to, regardless of which scorecard they’re running internally.
At its core, SPR quantifies the likelihood that a shopper exposed to a digital in-store media touchpoint will make a purchase. It does this by measuring product movement across three dimensions:
- Dollars spent — Incremental consumer spend driven by the activation.
- Units purchased — Incremental product volume moved during the campaign period.
- Shopper behavior — Purchase activity across defined shopper segments.
Together, these dimensions move the evaluation beyond a flat ROAS number to show whether the right shoppers bought more product and by how much.
Shopper segment definitions can and should vary by retailer and product category. SPR holds the flexibility while giving everyone a common structure to work from.
A Recap of Our Research
ISM, in partnership with Catalyst Media Consulting, interviewed leading brands, agencies, and retail media executives across the U.S. and U.K. to understand what’s actually preventing ongoing, incremental digital in-store investment. The goal was to define a measurement approach that resonates across teams and directly influences how budgets get allocated to digital in-store tactics.
The research examined in-store successes, pain points, and non-negotiables across stakeholder groups, focusing specifically on dollars spent, units purchased, and shopper behavior across segment types — the three dimensions of product movement. Across interviews, we noticed a consistent pattern. Regardless of company size, category, or market, every stakeholder ultimately focused on tracking whether the product sold and which shoppers it reached.
The industry’s problem wasn’t a lack of measurement sophistication. Instead, fragmented metrics, inconsistent definitions of success, and the absence of a shared framework across brands, merchants, agencies, and RMNs made it nearly impossible to compare results or build reinvestment confidence. Those patterns became the foundation for SPR.
The Four Scorecards
Four distinct stakeholder groups have been evaluating the same in-store activation against four completely different definitions of success:
- The Media Mix Scorecard (agencies): How does in-store perform relative to other channels in the media plan?
- The Retail Sales Scorecard (merchants): Did the activation move product off the shelf?
- The Media Revenue Scorecard (RMNs): Did the brand get enough return to reinvest?
- The Efficiency Scorecard (brands/shopper marketing): Did the activation hit sales targets and strengthen the retailer relationship?
Each scorecard is legitimate and reflects real business priorities. But when a brand’s media team demands detailed attribution and the merchant cares about moving product, those priorities collide and investment stalls before it scales.
SPR doesn’t replace these scorecards. It gives them a shared foundation. By anchoring evaluation to dollars spent, units purchased, and shopper behavior across segments, SPR feeds into each stakeholder’s existing framework without asking anyone to abandon it. A merchant can see product movement. A brand can see which shopper segments responded. An agency can connect in-store performance to the broader media mix. An RMN can demonstrate the return that justifies reinvestment.
That common structure is also what makes SPR comparable across retailers, formats, and audiences. Shopper segment definitions flex to fit the category and retailer context, but the underlying measurement logic stays consistent, giving every party a result they can actually act on.
The Metrics Behind SPR
SPR produces a matrix of metrics that span all three dimensions of product movement, dollars, units, and shopper segments, giving each stakeholder a clear line of sight into the numbers that matter most to their scorecard.
The core metrics are:
- Incremental sales (dollars spent): The extra revenue generated during an activation compared to a matched control group. It’s the core metric for brands evaluating ROI and RMNs building a case for budget reinvestment.
- Incremental units purchased: The extra product volume moved as a direct result of an activation. This is the top priority for merchants, who measure in-store success by their foundational metric, i.e., how much physical product moved off the shelf.
- SPR by segment: The rate of purchase activity broken down across loyal, occasional, lapsed, and new shoppers. This goes beyond a flat ROAS number by revealing exactly which buyer types drove the sales lift and by how much.
- iSPR (incremental SPR): Measured through matched-market tests, iSPR isolates the exact causal impact of a digital in-store activation on buyer behavior by stripping away baseline performance. It gives agencies a clean, comparable, and incrementality-based input for media mix modeling.
RMNs will continue to report iROAS as a standard output, and SPR is designed to complement that, not replace it. The difference is that SPR gives merchants an equally rigorous metric in the language they already use to evaluate in-store activations. For the first time, teams can evaluate a digital in-store activation on the same playing field as a traditional trade promotion by looking at whether it moved product, among which shoppers, and by how much.
How Is SPR Applied and What Does It Mean for Stakeholders?
SPR slots directly into existing workflows without requiring anyone to overhaul their processes, adding a unified layer of incrementality-based measurement across the entire retail media ecosystem. By translating in-store activity into a shared standard, it bridges the gap between media performance and merchant metrics, delivering unique value depending on your role in the ecosystem.
For brands
SPR eliminates post-campaign guesswork and delayed lift studies. Brands get clear visibility into segment-specific purchase lift and total units moved. Because the measurement framework is consistent across retail environments, brands can evaluate performance side-by-side to see where their investment works hardest—directly informing budget allocation, audience targeting, and creative strategy.
For retailers and RMNs
SPR strengthens the value story by shifting conversations from raw impressions delivered to true product movement—speaking the exact language merchants already trust. This standardized framework makes digital in-store media products easier to sell, defend, and differentiate, turning one-off test budgets into annual, always-on commitments.
For agencies
SPR provides a comparable, incrementality-based metric that sits right alongside traditional digital channels in media mix modeling. It removes the manual friction of stitching together incompatible RMN reports, giving agencies the data needed to hold in-store to the same scrutiny as other media and build stronger client recommendations.
While shopper segment definitions flex to fit specific category contexts, SPR’s underlying structure stays constant across different retail environments. Ultimately, this gives the industry a long-overdue common language—reducing friction, increasing transparency, and setting a consistent baseline to comfortably scale in-store media investments.
What Now?
SPR is designed to give every stakeholder a credible, shared answer to whether the product sold. The work to validate it is already underway. Phase 2 of this research is testing SPR against live activations across retail environments to confirm its predictive value and refine how shopper segment definitions translate across categories and retailers. Those results are expected in October 2026, and will build directly on the framework introduced here.
In the meantime, the full report is available now. If you want to dig deeper into the research, the methodology, or how SPR applies to your specific retail environment, it’s a good place to start. You can also reach out to the ISM team directly to learn how SPR can be integrated into your current measurement approach.
