1. Overview of Retailer X and the Pharmacy Industry

Retailer X is a U.S.-based online pharmacy serving a diverse national customer base. Its core shoppers are households with pets and health-conscious consumers seeking affordable, convenient access to essential pharmacy products. Retailer X’s value proposition lies in a wide product assortment, reliable shipping, and competitive pricing. With a long-standing presence in the U.S. market, the company has built strong loyalty, particularly among repeat customers.

From a media investment perspective, Retailer X relies heavily on Paid Search, which has consistently delivered the majority of new customer orders and remains the dominant channel in its acquisition mix. However, dependence on a single channel creates constraints for long-term scalability. To unlock sustainable growth, Retailer X has explored Paid Social advertising as a complementary lever for customer acquisition.

2. Business Challenge: Proving Prospecting Impact in Paid Social

While Paid Search remained the most reliable source of new customers, Retailer X wanted to diversify into Meta ads to scale growth. Retargeting campaigns on Meta showed clear impact through repeat purchases and mid-funnel engagement. However, prospecting campaigns – aimed at reaching net new customers – rarely generated direct, last-click sales. This created skepticism at leadership level, with concerns that budget allocated to prospecting could be wasted or misattributed.

The key challenge was proving the incremental value of Meta prospecting campaigns. Could they truly generate new sessions, revenue, and customers that would not have been acquired otherwise? Or did Meta’s platform attribution simply overstate performance? Retailer X needed rigorous, scientific evidence to validate whether Meta Prospecting deserved a larger share of budget. Without this clarity, the company risked under-investing in a growth channel or overspending based on inflated reports.

Relevant case study: How Brand X Used Competitor Keywords to Cut CAC and Win More Customers with AI-Led Search

3. Our Approach: Designing and Executing an Incrementality Test

We built a geo-based test covering 16% of Retailer X’s U.S. sessions. In these selected states, 84% of acquisition activities were paused during the tested month, while the control group continued with “business asusual.” This allowed us to observe whether exposure to Meta prospecting ads created measurable differences in sessions and revenue. To minimize cost, only a subset of prospecting campaigns remained active in test markets. Using our in-house Python framework, we cut design time by 50% and ensured statistically valid group selection.

Incrementality testing stages:

· Design: Defined the hypothesis and split geolocations into test and control groups.

· Treatment: Paused activity in the test group whilemaintaining normal campaigns in control markets.

· Measurement: Compared sessions and revenue betweengroups before and after the test period.

4. Results: Incremental Value Confirmed

The incrementality test revealed clear evidence that Meta prospecting campaigns delivered strong business impact. Sessions increased significantly in test geographies, with incremental sessions representing a 6% uplift compared to control markets. Revenue also grew meaningfully, showing a 5% lift directly attributable to prospecting activity.

Most strikingly, the test demonstrated that the true incremental ROAS of Meta prospecting was more than 28 times higher than the ROAS reported in GA4. This gap highlighted the limitations of platform and analytics attribution when measuring upper-funnel campaigns. With incrementality proven, Retailer X could explore scaling up prospecting spend, knowing it showed potential in driving meaningful growth beyond search and retargeting existing touchpoints.

Bullet point summary of results:

· 6% uplift in sessions from prospecting.

· 5% incremental revenue lift.

· Incremental ROAS 28x higher than GA4-reported ROAS.

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Struggling to steer Paid Social towards incremental growth? Reach out to us!

Relevant insights

· Case study: Measuring for incrementality makes Dunelm’s Facebook Ads 90% more effective ​

· Article: Organic vs. Paid Social Media: How to Balance Brand Trust and Performance Marketing

· Article: Which Ad Channel Wins When? Your Guide to Smarter Digital Spend

About Crealytics

Crealytics is an award-winning full-funnel digital marketing agency fueling the profitable growth of over 100 well-known B2C and B2B businesses, including ASOS, The Hut Group, Staples and Urban Outfitters. A global company with an inclusive team of 100+ international employees, we operate from our hubs in Berlin, New York, Chicago, London, and Mumbai.