Structural Biases in MMM are Penalizing Affiliate Marketing, New Prohaska Research Finds

New research reveals measurement flaws causing MMM to systematically misread affiliate performance

SAN MATEO, Calif., May 5, 2026 /PRNewswire/ -- A new research report commissioned by Rakuten Rewards and conducted by Prohaska Consulting identifies both a critical gap in how affiliate marketing is evaluated and the clear opportunity for brands willing to close it. The report, The Next Frontier of Measurement: Fair Evaluation of Affiliates in Marketing Mix Models, reveals that marketers have a challenging time to accurately rely on standard Marketing Mix Modeling (MMM) to assess affiliate performance. Affiliates are often a proven channel, but one that doesn't fit cleanly into the existing MMM evaluation framework.

The report from Prohaska Consulting, a leading digital media and advertising strategy firm specializing in data and measurement, draws on more than two dozen interviews with senior marketing leaders from major brands, alongside leading MMM providers. It includes analysis of real-world case studies and performance data from major retailers, agencies and Rakuten Rewards.

The central finding concludes that while affiliate marketing delivers strong returns, the models used to measure it simply aren't capturing them. For marketers, that may mean systematically underfunding a proven channel that reaches high-intent consumers at precisely the moment they're ready to buy, an audience that the research identifies as difficult to reach anywhere else.

"Most marketers don't realize how much affiliate performance is being underrepresented in their models, and that gap has real dollar impact," said Ameet Shah, Partner at Prohaska Consulting. "The capability to more accurately measure exists, but it's not being applied effectively. With consistent data inputs and alignment across the ecosystem, it can be."

The Performance Gap MMM Keeps Missing

Affiliate marketing is a proven and cost-efficient performance channel in digital advertising. More than 80% of marketers rely on affiliates, and data from Rakuten Rewards across thousands of brands shows a 17x return in sales versus commissions. Yet affiliate marketing remains consistently misrepresented by MMM when it comes to budget allocation decisions.

The case studies in the report illustrate the cost of that mismeasurement across a range of real-world scenarios. For example, when two brands under the same parent company ran programs concurrently on Rakuten Rewards, the actively managed program using elevated Cash Back tiers and time-limited promotions delivered up to 25x higher ROAS than its passive counterpart. In another case, a leading agency that properly segmented affiliate inputs in MMM and planning tools experienced a 10% lift in iROAS investments on loyalty publishers that would otherwise be lost when viewing affiliate marketing as a single bucket.

The consequences of acting on incomplete information extend beyond measurement. A major retailer that paused its affiliate program after questioning its incrementality drove customers to direct competitors and lost more than 50% of its prior volume. Even a year after reactivating its affiliate program, the retailer did not recover its customers or market position.

Two Structural Flaws That Cause MMM to Misread Affiliates

1. Lack of standardized data. MMM and marketers often lump cash back, coupon, content, comparison shopping, influencer, and loyalty into one broad affiliate classification, erasing the ability to observe real performance differences. And because affiliates are focused on conversion, they lack the data inputs that MMM relies on to measure other channels, such as impressions and clicks.
   
   
2. MMM can't do it alone. Because affiliates earn commissions on completed sales, their activity always tracks with revenue. MMM reads that as affiliates claiming credit for existing demand rather than driving new demand. Traditional MMM frameworks also prioritize the cheapest returns, overlooking the strategic value of scale-on-demand, one of the affiliate channel's significant advantages.

What the Research Recommends Changing

"We've sat across the table from brands that pulled back on affiliates because their MMM told them to do so, and they spent the next year trying to win back ground they didn't need to lose," said Carl Lurie Kalapesi, Chief Commercial Officer at Rakuten Rewards. "Affiliates deliver consistently and at scale, and this research gives marketers evidence and the framework to prove it. Getting the measurement right is more than just a technical fix. It is often the difference between growing market share or handing it to a competitor."

The report outlines specific steps for each part of the ecosystem:

Steps for Marketers:

• Break affiliates into sub-categories within MMM datasets rather than treating the channel as a single input
• Capture reward intensity and promotional offer changes as time-series variables (e.g. Cash Back rates, promotions, etc.) 
• Calibrate MMM with sustainable testing (geo holdouts, time-based cashback tests, audience-level suppression)

Steps for Publishers:

• Provide impression and click data to enable comparisons within MMM modeling
• Build testing capabilities that support geo-targeting, holdouts, and A/B experiments
• Develop direct data integrations with major MMM vendors

The recommendation for the industry:

• Establish shared definitions and taxonomies for affiliate sub-categories, giving the channel the same measurement footing as video, native, and display

To read the full report, The Next Frontier of Measurement: Fair Evaluation of Affiliates in Marketing Mix Models, visit LINK.

About Rakuten
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Media Contact:
Carol Lee
Rakuten
[email protected]

SOURCE Rakuten Rewards