This article explains what incrementality means in the affiliate channel, why it’s often questioned, and how different partner types can deliver incremental value across the customer journey. It also covers common metrics, things to avoid and how to measures incrementality in Awin.
What incrementality is
Incrementality is the additional value your affiliate activity delivers that wouldn’t have occurred without it. This can include:
New customers who discover and buy from your brand.
Higher basket values than your usual average.
Improved conversion rates when certain partners are involved.
Increased sales in key product categories.
How you define incremental value should align with your wider business and marketing objectives. Because partners play different roles across the customer journey, it’s often helpful to define incrementality differently for different partner types.
Why incrementality is often questioned in the affiliate channel
Questions about incrementality are raised across all marketing channels, but affiliate is often scrutinized more. One reason is the way incrementality is traditionally tested in other channels. Marketers commonly use A/B tests, comparing a test campaign to a control campaign and judging incremental value based on the difference in conversion rates.
Although this method can work, it creates challenges when applied directly to affiliate:
It misses the diverse contributions that partners make across multi‑touch journeys.
Only a limited group of partner types and promotion methods are suited to this type of test.
Evergreen content that consistently drives revenue can be overlooked.
It doesn’t account for variation between individual partners.
It’s challenging to implement and tends to be purely campaign led.
Because of these limitations, a more useful approach is to evaluate the incremental contribution of different partner types across the full customer journey, rather than treating incrementality as a single yes-or-no outcome for the whole channel.
How partners deliver incremental value across the purchase journey
Advertisers on Awin can work with a diverse range of partners who add value at each stage in the purchase journey. Scott Galloway’s clock model describes three core phases: pre-purchase, purchase, and post-purchase. The affiliate channel can deliver value in all three, which is why a more nuanced view of incrementality is required.
Pre-purchase
Pre‑purchase partners help users discover, research, and consider your brand and products. Examples include:
Influencers
Content partners
Display partners
Comparison shopping services
These partners often initiate purchase journeys and introduce new customers to your brand.
Purchase
Purchase‑stage partners focus on converting interested users into buyers. Examples include:
Brand partnerships
Incentive and cashback partners
On‑site technology providers
Retargeting partners
These partners can increase conversion rates, improve on‑site experience, and influence average order values.
Post-purchase
Post‑purchase partners help extend the value of existing customers by encouraging repeat orders or referrals. Examples include:
Referral marketing partners
Loyalty and rewards programs
This activity can drive incremental lifetime value beyond a single transaction.
Because affiliates contribute in each of these phases, incrementality can’t be fully captured by last‑click-only metrics or simple on/off tests.
Common metrics for measuring incremental value
You can use different metrics to understand incremental value, depending on your objectives and partner mix. Common examples include:
New customers: Partners who drive first‑time buyers.
Basket uplift: Partners associated with higher-than-average basket values.
Conversion drivers: Partners whose involvement increases the likelihood of conversion.
Purchase initiators: Partners who bring new customers into a purchase journey.
Full-price customers: Partners who deliver customers who pay full price.
Category sales: Partners who grow sales in key product categories.
You don’t have to use every metric. Focus on those that best align with your definition of incrementality and track them consistently.
What to avoid when assessing affiliate incrementality
There are several common pitfalls that can lead to misleading conclusions when assessing incrementality in the affiliate channel.
Using Google Analytics or GA4 as the primary view of affiliate value
A frequent error is to use Google Analytics or GA4 to decide whether a partner or campaign is incremental. For example, you might compare GA4 revenue with Awin reporting and assume that if GA4 shows lower revenue, the activity is not incremental.
However, GA4 often misses a significant number of affiliate touchpoints and doesn’t show every involvement in a customer’s journey. This makes it unreliable as the main way to measure channel value.
Judging all partners by the same goals
A well‑rounded affiliate program includes many partner types that deliver value in different ways. Assessing all of them by the same incremental metric ignores their unique roles in the journey. For example, top-of-funnel content partners can be important initiators, even if they are not the last click.
Relying on infrequent or one‑off tests
Single tests that fail to account for trading changes, competitor activity, or shifts in consumer behaviour can misrepresent actual incremental value. Without repeated testing, it can be difficult to separate genuine incremental uplift from short‑term fluctuations.
Using blackout testing without understanding the risks
Some advertisers try to test incrementality by turning off certain partners or partner types and observing the impact. This blackout approach can:
Overlook long‑term benefits that are not visible in a short window.
Lose market share to competitors.
Damage partner relationships.
In one example, a large home improvement retailer performed blackout testing and lost all market share, while their closest competitor increased their share by 8%.
How to measure incrementality in Awin
Because so many partners contribute to the full customer journey, Awin uses attribution technology to show how partners support common incremental goals.
Key metrics include:
Conversion impact: How conversion rate changes when a partner is involved at any point in the journey.
Basket boost: The uplift in basket value when a partner participates in the customer journey.
Initiator ratio: The proportion of sales involving a partner where they initiated the sale.
The Publisher Incrementality report monitors the incremental value partners deliver at all stages in the conversion path and analyzes performance across these metrics. This helps you understand which partners are contributing most to your incremental goals.
Plan availability
Publisher Incrementality report is available only for Awin Advanced customers.
Key takeaways
To make incrementality work for your affiliate program:
Be clear about what incremental value means for your business.
Align your definition with both commercial and marketing objectives.
Use metrics like new customers, conversion impact, basket boost, and initiator ratio that reflect that definition.
Avoid relying on GA4 alone or judging all partners by the same metric.
Recognize that partners add value throughout the entire customer journey.
Use Awin metrics and partner data to understand and improve incremental value.
FAQ
Can I use GA4 to decide if a partner is incremental?
You shouldn’t rely on GA4 alone to assess incrementality. GA4 often misses affiliate touchpoints, so comparing GA4 revenue with Awin reporting can make incremental activity look less valuable than it really is.
Do all partners need to be measured in the same way?
No. Different partner types play different roles in the journey. It’s often more accurate to define and measure incrementality differently by partner type. For example, using new customers for some partners and basket uplift or initiator ratio for others.