CPG · Answer

Is incrementality a better metric than ROAS in retail media?

Only if somebody outside the network checks how it was calculated. Incrementality is the category's answer to untrustworthy ROAS, and nearly every network now reports a version of it. But Albertsons Media Collective's own March 2026 research found iROAS can vary 6.5x, and flips the result in 83% of campaigns, depending on filtering, matching and revenue-calculation choices. Those choices belong to the network. A control group, a set of matching variables and a revenue definition are three places to put a thumb, and none is visible to the buyer. Unaudited, iROAS is not a more honest number than ROAS — it is a number with more discretion inside it.

The evidence

The variance finding comes from a seller of incrementality.

Albertsons Media Collective operates a retail media network and sells incrementality reporting. It published the research showing its own headline metric swings 6.5x on methodology. Read as an admission against interest, which is what makes it carry more weight than an agency complaint would.

No incrementality metric is independently accredited anywhere.

Zero networks hold MRC accreditation on incrementality, attributed sales or ROAS. The only outcome metrics in the MRC pipeline are Kroger's, in pre-audit since June 2026 and not yet granted. Every iROAS figure a brand is quoted today is self-graded.

Most networks do not publish the method at all.

Walmart Connect announced incremental sales measurement for Sponsored Search without publishing a methodology. Instacart's sales lift testing methodology is not public. Roundel's Matched Market Model is secondary-sourced. Kroger and Albertsons document test-and-control designs; most of the category documents nothing.

The deeper problem is that it blocks improvement, not just comparison.

Optimisation needs an objective the optimiser did not write. A network tuning toward a figure whose methodology it controls cannot distinguish getting better from counting differently, and over enough cycles the system learns the counting. That is a capability limit, not an honesty one, and it applies even to networks acting in good faith.

What would have to be true for this to be wrong

If a network will hand you its control-group construction, its matching variables and its revenue definition, and let you re-derive the lift from log-level data in your own environment, then its iROAS is worth more than anyone's ROAS and you should weight it accordingly. Ask for those three things by name. The request costs nothing and the answer sorts the category faster than any benchmark.

Albertsons Media Collective iROAS variance research, March 2026. MRC digital accreditation directory and services-under-review listing, checked September 2026. Network methodology disclosure from each network's own documentation. Desk review, 22 sources, no instrument run.
Every row behind this answer is published in the standing study at cultmath.com/research/marketing/open-loop-retail-media, which is re-run on a schedule and corrected in place, dated.
Published 2026-11-09 by Ipalibo Da-Wariboko, CULT+MATH LLC. Where a number could not be sourced, this page says so and gives none.

This is one of six decisions covered in the cpg decision brief — each with the evidence behind it, who owns it, who it is contested with, and what would have to be true for the answer to flip.

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