Retail Media Incrementality | Behind Sam's Club MAP's Rest-of-Market Report

This episode unpacks Sam's Club MAP's new Rest-of-Market (ROM) analysis — a retail media incrementality study that actually names its control group, uses a deterministic identity layer (logged-in member IDs and SKU-level household matches), and reports an iROAS net of baseline rather than a blended gross. We walk through what that means, why that combination is rare, and how to use it as a test against every other RMN you're buying from — Walmart Connect, Kroger Precision, Target Roundel, and the rest.

What we cover:

• What incrementality actually is — the one-line subtraction (iROAS = (revenue with ads − revenue without ads) / ad spend), and why constructing an honest control group is the hard part, not the math
• Why last-touch ROAS has survived a decade of known-misleading-ness — the quiet incentive alignment between platforms, brand teams, and finance leads that keeps the fiction in place
• What Sam's Club's MAP and ROM report do differently — deterministic member IDs as the identity spine, SKU-level matches extending to partner retailers, real members on both sides of the subtraction instead of modeled audiences or look-alikes
• The three-question framework for pressure-testing any RMN's incrementality claims — (1) is there a real, observable control group? (2) is the identity join deterministic or probabilistic? (3) is the reported iROAS net of baseline or gross?
• What typical vendor answers look like — and what "we estimate baseline using predictive algorithms" really tells you
• How gross ROAS and net iROAS usually diverge — why a 5x gross often collapses to a 1.2x–1.5x net, and why that range is often still worth buying but a different budget conversation
• The disclosure curve from here — why Kroger Precision, Target Roundel, and Walmart Connect all have CFO customers asking the same questions, and what the budget reallocation across a year probably looks like
• A practical move for this week — how to pressure-test one of your own retail media contracts, and why the stalling pattern is itself the answer

Closing question we leave you with: how will true retail media incrementality change the way you plan your next campaign?

---

Want to practice this exact business problem? Go to marketingcasebootcamp.com for hands-on case simulation practice on this exact business problem — so when you're in the boardroom, you know what to ask and how to spot the accounting fictions.

If this episode was useful, share it with other marketer folks — especially anyone still trusting a last-touch dashboard to dictate their budget.

Read the full written case on Marketing Case Bootcamp.

Read the original Sam's Club MAP announcement on Walmart Corporate.