Marketing Mix Modelling (MMM) is rapidly moving up the agenda for larger advertisers, and with it comes significant risk for the affiliate channel.
Done well, MMM has the potential to demonstrate the true value of affiliate marketing beyond last-click attribution. Done poorly, it risks undervaluing the channel because the data available to the models is incomplete or inconsistent.
Over recent weeks, we’ve been speaking to APMA members and brands to better understand how MMMs are being used in practice. Experiences substantially vary, but some common themes have emerged.
The biggest challenge appears to be data quality. Many paid media channels benefit from impression-level data and tightly integrated measurement across platforms. Affiliate marketing, by comparison, often relies on more fragmented data sources. Often impression data is not available which is a staple requirement of MMMs.
If affiliate touchpoints aren’t captured consistently, or network data isn’t fed directly into measurement platforms, the channel can appear to contribute less than it actually does.
Lack of granularity
Members have also highlighted concerns that affiliate marketing is too often treated as a single channel where individual affiliates or affiliate types are not split out.
Affiliate marketing is digital in microcosm offering brands the opportunity to partner with publisher businesses across the sales funnel.
High-quality content publishers, loyalty partners, comparison sites and technology partners all play very different roles in the customer journey, yet many models fail to distinguish between them. This can mask genuinely incremental activity while allowing poor-quality or non-incremental activity to influence perceptions of the entire channel.
For those long in the affiliate tooth, these problems will feel like the old attribution debate of 15 years ago resurfaced.
Other issues
At the same time, there was broad agreement that the industry also needs to look inward. Incrementality testing, better programme management and stronger compliance all have an important role to play. If we want advertisers to trust the outputs of MMMs, we also need confidence that affiliate programmes are delivering genuine value.
Finally, there is a clear desire for greater collaboration between affiliate networks, attribution providers and MMM vendors. Understanding which data sources are being used, how affiliate data is integrated, and whether richer signals such as impressions or engagement metrics can be incorporated will be critical if the channel is to be measured fairly.
What our research tells us so far
Alongside speaking to members, the APMA has launched what we believe is the first affiliate marketing survey examining how Marketing Mix Models are measuring affiliate and partner marketing.
Although the research is ongoing, several clear themes are already emerging:
- Around seven in ten respondents already use MMMs, either as their primary budgeting tool, alongside attribution, or are actively implementing one.
- Incrementality is the number one measurement challenge, with many advertisers struggling to demonstrate the full contribution of affiliate marketing.
- Affiliate is frequently treated as a single channel, rather than being broken down by publisher type or partner category.
- Upper-funnel and cross-channel measurement remains one of the biggest concerns, particularly for content, influencer and comparison partners.
- AI search and LLM-driven customer journeys are already appearing as an emerging blind spot that existing measurement approaches struggle to account for.
Perhaps the most significant finding is that brands aren’t rejecting MMMs. Instead, they’re asking how affiliates can be represented more fairly and accurately within them.
What brands are telling us
Our survey also contains free-text questions which allow brands to share their experiences and views:
Affiliate is too often treated as one channel
Many respondents said MMMs fail to distinguish between cashback, loyalty, content publishers, influencers, CSS, comparison sites and technology partners. By grouping everything together, genuinely incremental activity can be hidden behind lower-value activity elsewhere in the programme.
Incrementality remains the industry’s biggest challenge
Brands recognise the importance of proving incremental value, but many believe current measurement approaches don’t provide sufficient confidence. Several called for clearer guidance on testing methodologies and best practice.
Data limitations are skewing results
Respondents repeatedly highlighted concerns around incomplete tracking, inconsistent implementation, limited impression-level data and conflicting reporting between affiliate platforms, GA4 and attribution providers. The quality of the model will always depend on the quality of the data being fed into it.
Internal confidence matters
Several advertisers described increasing pressure from finance teams and senior leadership, who are placing growing weight on MMM outputs when making budget decisions. That makes accurate measurement more important than ever.
AI is creating the next measurement challenge
A number of brands are already thinking beyond today’s attribution challenges. As AI search and LLM-powered discovery become more prevalent, respondents highlighted the need for new ways of understanding how affiliate publishers contribute to customer journeys that don’t necessarily involve a traditional click.
What is the APMA doing?
Brand Survey
If you’re a brand or advertiser and haven’t shared your views, you still have time. The more responses we have, the more targeted our future support and guidance will be. The survey can be filled in anonymously and shouldn’t take up more than five minutes of your time.
You can fill in the brand survey hereOutreach to MMMs
One of the questions in the survey asks which MMMs brands are using. We want to identify the most commonly used solutions and contact them to understand better how their technology measures affiliate marketing.
Best Practice & Guidance
Ultimately, we want to produce best practice and guides to help brands better implement MMMs and measure the full contribution of the affiliate channel.
Member output
Some APMA member companies have already produced guidance and reports that help build knowledge around MMMs.
We are collating this information. You can find the current crop of guides below.
MMM Undervalues Affiliate Marketing, Forcing Marketers to Adapt
Lost in Translation: The Challenges of Media Mix Modeling in Gauging Affiliate Success
From clicks to clarity: How Media Mix Modelling is redefining measurement in affiliate marketing
