Incrementality: Affiliate Marketing’s Holy Grail

Incrementality is key to understanding affiliate performance. Discover how incrementality can give you total confidence in your affiliate program.

One of the biggest questions brands ask their affiliate manager is if their program is bringing in a return.

Brands invest in affiliate publishers not just to capture transactions, but to enhance performance across key business metrics. As a result, the value of an affiliate program extends beyond the last-click sale.

A well-executed affiliate strategy ensures brands reach and influence consumers in ways they otherwise wouldn’t. This can include partnerships that introduce the brand to new audiences, promotions that accelerate decision-making, or the creation of educational content.

This means the goal isn’t just to track whether a sale happened through an affiliate. Instead, we must understand how affiliates drive higher-value customers and contribute to overall business growth.

So how can brands be sure about the value of their affiliate program? The answer is incrementality.

What is incrementality?

Incrementality measures the true impact of a marketing channel by assessing how it influences key business outcomes beyond just conversions.

Instead of focusing solely on whether a sale would have happened anyway, incrementality helps brands understand how affiliates:

• Drive incremental revenue.
• Expand audience reach.
• Strengthen customer engagement.
• Improve conversion efficiency.

These measurements account for external factors to provide a clearer picture of the channel’s overall contribution.

Typically, a digital media strategy that includes affiliate marketing differs significantly from one without it. This extends beyond terms of revenue. We must also consider how it enhances customer acquisition, accelerates purchase decisions, and amplifies brand exposure.

With incrementality, we must do more than determine if an affiliate is bringing in new customers. We should identify how affiliates add value across the entire customer journey, influencing intent, loyalty, and long-term growth.

In short, incrementality determines whether the outcome would have been the same without introducing affiliate to the marketing funnel.

Why does incrementality matter in affiliate marketing?

Marketing experts generally consider affiliate a low-risk channel. The greatest risks are overpaying or giving discounts to acquire customers that would have converted without the program.

Naturally, brands don’t want to pay publishers or reduce prices to acquire customers who are already likely to convert.

Affiliate marketing agencies like Gen3 aim to isolate the affiliate program’s incremental performance to show its impact. This results in maximized program performance, enabling brands to make the most of their investment in the channel.

With this in mind, we recommend using directional data to correlate and understand consumer behavior.

What does the data say about affiliate incrementality?

When calculating incremental sales, it’s tempting overfocus on whether someone would have bought through a different channel.

This answer is seldom black and white. So many factors influence a purchasing decision. These factors often include dozens of brand touchpoints, the affiliate channel among them.

When brands measure incrementality, they often fixate on the “survey of one.”

It’s essential to stay realistic. We’ll never fully know if John Smith would have bought something without seeing this single affiliate placement. The modern customer journey usually presents buyers with an array of ads before they convert.

Few customers convert after just one or two touchpoints. When you examine the full marketing spectrum, you could be looking at as many as 50 touchpoints. This holds especially true when customers aren’t in dire need of a product.

This leads us to our next question.

Incrementality helps brands go beyond last-click attribution and understand real business growth.

How do you measure the true impact of your affiliate program?

We all want to understand how affiliate programs contribute to overall business growth.

While sales are a key metric, the true value of affiliates extends beyond just transactions. They help attract new audiences, shape purchasing decisions, and create additional touchpoints that move customers through the buying journey.

This is important when a brand is investing in multiple marketing channels. It becomes critical to assess how affiliates complement and enhance broader strategies rather than just attributing last-click conversions.

Fortunately, major case studies have already proven the value of affiliate channel partners.

A Commission Junction study surveyed 21 million retail consumers and 5.5 million transactions. The findings revealed that consumers who interacted with the affiliate channel had:

• 46% higher shopper to customer conversion.
• 29% higher spend per customer.
• 88% higher revenue per customer.

In other words, affiliate channels drive major value through incremental impact. They’re customer-centric, lending credibility to brands that might not be as well-known or trusted, and serve as an unbiased resource.

How do you measure affiliate channel sales incrementality?

Sales incrementality looks beyond whether individuals would have purchased without the affiliate channel influencing their decision.

Here are some things the affiliate experts at Gen3 look at to measure affiliate marketing campaign performance.

Understand how each publisher works.

In affiliate marketing, not all publishers are created equal. Some drive more sales than others. Some are more geared to a particular niche or audience than others. They might operate in different parts of the purchase funnel.

We suggest first understanding how each publisher works and how they fit into the bigger picture. Knowing their role in your larger affiliate ecosystem can help you better understand their impact.

Evaluate each placement in context.

When you have an array of publishers in your affiliate program, it’s important to account for both nuances and shared trends.

For example, when Slickdeals has a good day, Ebates/Rakuten Rewards tends to have a good day, too.

Diving deeper, we found this was because there’s a huge overlap in audiences. People who want to take advantage of a deal on Slickdeals also shop through Rakuten Rewards to get their cash back.

Context is crucial when evaluating the effectiveness of your affiliate partners. In the example scenario, users visiting Rakuten are pretty much ready to buy. They’re generally not going there to learn and research.

Evaluate the context of your placements based on where your customers are in the sales funnel. This can help you better understand the nature of your conversions.

Measure a wider spectrum of KPIs.

Looking beyond surface-level data is a major benefit of working with an affiliate agency like Gen3. This provides a clearer picture of conversion performance.

It’s not just about looking at the number of sales coming through the channel itself. At the publisher level, you could look at lead costs, average order value, click-through rate, and conversion rate.

You can also look at:

• The number of new products bought.
• Total sales after the affiliate offer.
• New customer revenue.
• Whether you’re selling add-ons.
• Whether you’re seeing more activity from specific promotions.

When measuring incrementality, we must also consider the organic lift an affiliate could contribute. For instance, what might the platform have driven that day without the affiliate?

These are all things that your affiliate will drive beyond a particular sale and basic ROI calculations.

Incrementality is not just about sales—it’s about customer engagement, audience expansion, and long-term value.

Affiliate incrementality is key; the best agencies will provide it.

A complicated topic, marketing incrementality is critical to understanding the overall performance of your affiliate program. Proper analysis leads to better decision making. This can include how much to invest in the channel and how to make that investment pay off.

Naturally, this is an area where an expert partner like Gen3 Marketing can make an enormous impact. Our experts can analyze relevant data, leading to actionable insights that put you on the road to success.

Learn what we can do to maximize your affiliate program. Contact us to speak with an expert today.

More Blogs