Affiliate marketing offers a valuable channel for driving conversions, but measuring its impact can be challenging, particularly when trying to employ techniques like randomized control trials (RCTs) or geo tests. For many marketers, these trials are considered the gold standard for determining the effectiveness of a campaign. However, applying RCTs to affiliate marketing presents several obstacles.
The Challenge with RCTs in Affiliate Marketing
Visibility Issues: The primary challenge with using RCTs in affiliate marketing is the difficulty in controlling visibility. Unlike digital ads, affiliate content (such as articles or blog posts) is often user-discoverable across a wide range of publishers. Making these articles or affiliate links visible to some users while hiding them from others is nearly impossible without restricting access to specific users, which most publishers can't feasibly manage.
Geographic Limitations: Another common approach to measuring incrementality is geographic holdout testing, where a campaign is paused in specific regions to observe changes in performance. However, this method isn't straightforward within the U.S., where affiliate links or discount codes cannot be restricted easily across state lines. While such testing is possible at the country level (by having offers only be valid in certain countries), this introduces another challenge: the assumption that media responsiveness is consistent across different countries. This assumption can be problematic since factors like media landscapes, brand strength, and consumer behavior can vary significantly across national borders, often more so than across different states.
Given these constraints, marketers need to explore alternative strategies to measure the effectiveness of affiliate marketing without relying on traditional RCTs or geo tests.
Alternative Approaches to Measuring Affiliate Marketing
Since standard randomized control trials and geographic holdout tests are not feasible, marketers have two primary alternatives to consider:
1. Temporarily Shutting Off Affiliate Marketing
One approach is to temporarily halt parts of your affiliate marketing efforts and observe the impact on conversions during this “dark” period. Focus on the most low-funnel elements of your affiliate marketing for this measurement strategy, such as coupons or cashback rewards. These activities are directly tied to purchase behavior, and any impact from their absence should be observable relatively quickly.
Here are some steps to implement this strategy effectively:
- Use Pulsing Strategies: Consider pulsing your affiliate marketing on and off for defined periods—such as two weeks on, two weeks off. This approach limits the opportunity cost of going dark and allows you to conduct multiple test periods to gather more robust data.
- Shorten Offer Validity: By limiting the validity period of certain offers, you create natural “on” and “off” periods that can help identify changes in consumer behavior and conversion rates. For instance, you could shorten a coupon’s validity to a month rather than have it be valid indefinitely. Observing conversion patterns in the weeks following can help gauge the offer’s impact.
2. Segment by Product Categories
Instead of halting all affiliate activity, restrict the use of specific coupons or cashback offers to only a subset of product categories. Narrow the range of products covered by the affiliate offer, and compare the performance of covered vs. non-covered categories. This tactic allows you to maintain affiliate engagement while still collecting valuable data on offer effectiveness. This can provide insight into the direct impact on those specific categories without broadly affecting all marketing efforts.
Here are some steps to implement this strategy effectively:
- Check for historical correlation: Ensure that the sales of the product categories included in the test are highly correlated with those not included. This way, any observed changes can be more confidently attributed to the changes in the affiliate strategy.
- Match the product attributes between test and control: To the extent possible, try to make the test and control groups of product categories similar in terms of price, timeline to conversion, availability etc. Having a group of test products which are much lower price than the control, for instance, will bias the test since shopping behavior is likely to be very different for items at vastly different price points
Communicating and Managing Internal Expectations
While these strategies can offer valuable insights, they come with trade-offs, including the potential for reduced sales during test periods or temporary customer dissatisfaction due to changing offers. It’s crucial to manage internal expectations by communicating the purpose and benefits of these tests. Emphasize the long-term value of understanding the true impact of affiliate marketing on overall performance, which can lead to more optimized spending and better resource allocation.
Customer service teams are often the first to hear from consumers about issues with offers, such as confusion over changing coupon terms. By working closely with this team, you can proactively address potential customer dissatisfaction and protect your brand’s reputation during testing periods.
Conclusion
Measuring the impact of affiliate marketing is no small feat, particularly when traditional RCTs aren’t an option. However, by exploring alternative approaches—like temporarily shutting off parts of your affiliate marketing, optimizing the validity and timing of offers, and collaborating with customer service—marketers can still gain meaningful insights into the effectiveness of their affiliate campaigns. While these methods may require more creativity and coordination, they ultimately enable a more data-driven approach to optimizing affiliate marketing efforts.
By thoughtfully applying these strategies, your team can navigate the complexities of affiliate marketing measurement and make more informed decisions that drive growth and efficiency.
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