In‑Store Retail Media: There’s More to Measurement Than ROAS
What is ROAS?
First off, you might ask: what is ROAS?
ROAS stands for Return on Ad Spend and it is a widely used marketing metric that measures the gross revenue a business earns for every dollar (or euro) spent on advertising. It's a powerful, metric, and for good reason: it gives brands and retailers a fast, comparable read on campaign performance.
In the rapidly growing world of retail media, it has become a cornerstone of how performance is communicated and decisions are made.
Why ROAS Became So Important in Retail Media
Retail media has grown into one of the most exciting and effective channels available to brands, and in-store retail media in particular offers something genuinely powerful: the ability to reach shoppers at the exact moment they are making decisions.
When shoppers are already at the shelf, a meaningful part of their decision-making journey is already underway. In-store media can greatly influence that moment, reinforcing brand preference, prompting a switch, or triggering a purchase that might otherwise have been deferred.
The question isn't whether in-store media works. It does.
The question is: how much of what ROAS as a metric reflects the impact of media versus purchase intent that was already there?
Incrementality: The Question ROAS Can’t Answer Alone
The question that unlocks the full picture is: would this sale have happened without the media?
That's incrementality, and the most reliable way to measure it is through test vs. control across matched stores. Media running versus media not running in similar stores, with the difference carefully measured.
This approach doesn't undermine retail media. It strengthens it. It separates sales generated because of the campaign from sales that happened during the campaign and that distinction is what allows brands and retailers to invest with real confidence.
Some campaigns that look strong on ROAS show even stronger incremental lift when tested properly. Others reveal opportunities to optimise. Either way, you're working with better information.
Halo Effects: Where In‑Store Media Often Over‑Delivers
If incrementality tells you whether it worked, halo tells you how much it really worked and this is where in-store retail media often surprises to the upside.
Retail media doesn't just influence what someone buys. It shapes how they shop, and that has meaningful knock-on effects across the basket and the brand.
Research from SMG supports this. A significant share of incremental sales from in-store media is driven beyond the featured SKU. That's a compelling story that standard ROAS simply doesn't tell.
Three Examples of Halo Showing Up in Practice
Product Halo
A campaign promotes one SKU, but the wider range lifts too. A report focused on the hero product might call it modest. The full category view tells a much more positive story.
Basket Halo
Shoppers don't just buy a product, they buy into a moment. Dinner. Hosting. A treat. Basket value often moves more than the advertised SKU alone, which means ROAS, measured narrowly, can genuinely understate what's happening.
Channel Halo
In-store exposure doesn't stay in-store. It drives recall, reinforces brand preference, and can influence online behaviour long after the shopper has left the aisle.
None of these effects show up cleanly in a standard attribution model which means brands relying solely on ROAS may be undervaluing some of their most effective activity.
Why This Matters for Retail Media Investment
As retail media investment grows, so does the need for measurement that reflects its full value.
If in-store media is judged purely on ROAS, there's a risk of two things happening:
Budgets gravitate toward credit-capturing tactics high ROAS activity that reaches shoppers who were already primed to buy, at the expense of formats that build broader demand.
And genuinely powerful growth drivers, the formats that influence behaviour across the basket, the range, and the longer-term relationship with the brand get undervalued simply because they don't convert as cleanly in attribution models.
Better measurement doesn't diminish retail media. It makes the case for it more robustly.
A More Complete Measurement Framework
Moving beyond ROAS doesn't mean abandoning it, it means giving it proper context.
A fuller framework for in-store retail media could include:
Incremental ROAS (iROAS)
Revenue that exists only because of the campaign. Calculated as incremental revenue divided by ad spend, iROAS helps retail media teams demonstrate real, net-new impact and have more confident conversations with brand partners.
Halo Impact
Total category and basket uplift, not just the featured SKU. This is often where the most compelling part of the in-store story lives.
New-to-Brand (NTB)
Is the campaign growing penetration, or activating existing buyers? Both have value but knowing which one you're achieving changes how you plan and how you optimise.
Together, these give a far more complete and usually more impressive view of what in-store retail media is actually delivering.
Where Next
ROAS remains a valuable tool. But the full value of in-store retail media the halo, the incrementality, the basket effects is bigger than any single metric can capture. The channels that prove that convincingly will attract the investment they deserve.
Full disclosure: earlier in my career, I helped develop a media optimisation platform focused heavily on ROAS and I have genuine respect for what the metric does well