# Case Study: A Growing Top Line Was Hiding a Worsening Unit Cost | Crank Source: https://wearecrank.com/case-studies/luxury-department-store-behavioural-2022 Search users converted three times better and content viewers 44% better — both reaching under a quarter of visitors — while cost per acquisition rose 25% inside a year that looked healthy on every headline number. --- Luxury Department Store — 2022 Audit # A Growing Top Line Was Hiding a Worsening Unit Cost Search users converted three times better and content viewers 44% better — both reaching under a quarter of visitors — while cost per acquisition rose 25% inside a year that looked healthy on every headline number. Challenge Total advertising cost fell 14 per cent year on year while cost per acquisition rose 25 per cent to £20 and revenue grew 20 per cent — a set of headline numbers that all looked healthy at once, while unit economics quietly worsened underneath them. Approach Look at behaviour rather than only spend: which visitors already converted better, which departments were carrying the site, and how much cross-department demand was going unexploited. Outcome Shoppers who used site search converted three times better and content viewers converted 44 per cent better — both reaching under a quarter of visitors — while conversion varied nearly six-fold between departments of the same shop, none of it visible from the headline revenue and cost figures alone. 01 ## Behaviours that predicted conversion, reaching almost nobody Across a £3.1m month, visitors who used site search converted at 7.9 per cent against 2.5 per cent for those who did not — in the strongest department the gap was 15.0 against 5.4\. Only 21.6 per cent of shoppers ever used search. Visitors who viewed editorial content converted at 5.2 per cent against 3.6 for those who did not, a 44 per cent lift reaching just 4.0 per cent of shoppers. Two of the largest measurable behavioural differences on the site, each available to only a small fraction of visitors. 02 ## One site, six-fold difference inside it Department conversion ranged from 1.5 to 8.8 per cent for new shoppers, with average order value ranging from £96 to £317 and cart abandonment from 62 to 86 per cent — inside one website. New shoppers converted at 4.1 per cent against 6.8 for existing ones, and the gap held across all four departments; new shoppers made up 86 per cent of visitors, so a blended figure flattered acquisition and understated the returning customer base. Between a third and two-fifths of customers bought outside the department that brought them in — 22 to 38 per cent, with clear repeating pairings — and no cross-selling activity had been built around any of it. 03 ## A cost problem hiding inside a growing top line Total advertising cost fell 14 per cent year on year while cost per acquisition rose 25 per cent to £20, driven by shifts within paid search and shopping. Revenue was up 20 per cent, so every headline figure looked healthy throughout — a deteriorating unit cost concealed inside a growing business. The analysis itself was careful to flag its own limits before drawing conclusions: basket behaviour was recorded inaccurately, traffic sources were being misrepresented, and year-on-year comparison was constrained by data retention — stated at the front of the report rather than discovered later, so a reader could tell which findings were solid and which provisional. ## What behavioural data showed that the headline figures didn't 7.9% vs 2.5% Conversion rate, search users vs. non-searchers 1.5%–8.8% Conversion rate range, across departments of one site +25% to £20 Cost per acquisition, even as total cost fell 14% 22%–38% Customers buying outside the department that brought them in Drawn from Crank's account audit conducted in 2022 for this luxury department store. Client not named. ## 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)