# Case Study: Why the Blended Return Was the Least Useful Number in the Account | Crank Source: https://wearecrank.com/case-studies/is-clinical Existing customers returned nearly three times what prospecting did — and a creative test that went the opposite way to what the account expected. --- Beauty & Skincare Case Study — iS Clinical # Why the Blended Return Was the Least Useful Number in the Account Existing customers returned nearly three times what prospecting did — and a creative test that went the opposite way to what the account expected. Challenge A single blended return on spend was standing in for two very different questions — what it costs to win a new customer, and what it costs to keep one — while revenue grew 79 per cent and the blended figure fell regardless. Approach Separate acquisition from retention in reporting and bidding, and test creative on its own terms rather than assuming last year's winning format still applies. Outcome Once separated, existing customers returned 10.06 times spend and produced 80 per cent of the channel's revenue, against 3.70 for prospecting — and a creative test that went against the account's own expectation confirmed that format has to be proven per account, not assumed. 01 ## A known audience, worth protecting The existing newsletter audience converted at 17.89 per cent during a seasonal sale, against zero for general Meta targeting reaching a cold audience over the same week with the same offer. A same-week, same-offer comparison, not an inferred effect. 02 ## A creative test that didn't go the expected way Standard branded creative was tested against user-generated content twice: once during a seasonal event, where standard creative returned 3.42 times spend against 0.84 for user-generated content, and again the following quarter, at 7.83 against 1.05\. The user-generated test itself was underfunded both times — one advert with no offer behind it, then three videos on £196 of spend — which is itself part of the finding: a format can't be judged on a test too small to produce a real answer, in either direction. Click price moved in a way that didn't predict the outcome either. In one comparison, the cost of a click rose 436 per cent, and the cost of a new customer rose 305 per cent alongside it — a case where the two numbers moved together, which on its own tells you nothing about whether that's typical, only that click price cannot be assumed to track acquisition cost reliably in either direction. 03 ## What retention actually returns In the first quarter of a full year of separated reporting, existing customers returned 10.06 times spend on Meta and produced 80 per cent of the channel's revenue, against 3.70 for prospecting. Within that same existing-customer activity, image creative returned 10.81 against 4.34 for video. Widened across the rest of the account, retention returned 8.6 times spend against 3.4 for acquisition. A blended figure across all of this would land somewhere in the middle and describe neither audience accurately — prospecting at 3.70 is a perfectly serviceable acquisition return on its own terms, and retention at over 10 times spend is exceptional. Judged on the blend, the first looks like it's failing and the second looks merely decent. 04 ## What growth cost, and what's still open Across the year, revenue grew 79 per cent to £960,000 on 122 per cent more spend, with purchases up around 79 per cent. Blended return on spend fell 19 per cent, to 4.51 — the arithmetic of pushing harder on acquisition, which returns less than retention, while nothing about the underlying business got worse. Paid media rose from 51 to 77 per cent of total revenue over the same period, all traced through and verified against the reporting database. After three consecutive years of running the same seasonal campaign, the account's own recommended next step is still to understand new customer lifetime value from the sale — evidence that measurement maturity doesn't accumulate automatically just because a campaign repeats. The mechanism behind this year's growth is evidenced. What the acquired customers are worth over time is not yet measured. ## What separating acquisition from retention actually showed 10.06xvs3.70x Return on spend, existing customers vs. prospecting 80% Of channel revenue from existing customers alone +79% revenue/\-19% ROAS Same year — growth pulling the blended figure down 3 years Running the same campaign, LTV still not measured Figures drawn from Crank's own managed-account data and account reviews for iS Clinical, 2023–2026\. 2025 figures verified against the reporting database. ## Want to know what this looks like in your own account? These findings came from asking straightforward questions before any budget moved. We're happy to do the same for yours. [ Talk to Wearecrank](https://wa.me/447457416922?text=Help%20my%20business)[Get in touch](/contact) [← Back to all case studies](/case-studies)