Why Good Measurement Starts Outside the Platform
March 24, 2026
This piece was written and published by Cardinal Digital Marketing, a company that sells healthcare performance marketing services. It is included here for its practical insight. Its inclusion does not mean that Healthcare Growth Strategies, its founder, or his employer endorses, recommends, or has a position on Cardinal Digital Marketing or its products. Figures drawn from the vendor’s own customer or platform data have not been independently verified.
Good measurement starts with a source of truth outside the ad platforms, usually a CRM that records every lead and its stage, according to Cardinal Digital Marketing’s Ignite podcast. Alex Kemp, Cardinal’s senior director of analytics, warns that a blended CPA can hide inefficient spend: if an extra $10,000 brings in 10 patients, the marginal CPA is $1,000 even when the blended figure stays under a $300 target. He suggests adding a delta column to month-over-month reports, dividing the change in cost by the change in new patients. Platforms can also over-count, for example 2,000 reported conversions against 1,500 actual new patients, often from view-through credit. Kemp recommends triangulating last-click attribution, media mix modeling and incrementality tests.
Multi-site groups often scale paid media by watching platform-reported CPA, which can reward spend that adds few real patients. Tracking marginal CPA, treating view-through conversions as assists and reconciling platform totals against new patients in the CRM are steps a marketing team can start this month without new tools.
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What is the blended CPA trap in healthcare marketing?
A blended cost per acquisition can look on target while extra spend brings in patients at a much higher marginal cost. Cardinal’s example: $10,000 of added spend yielding 10 patients is a $1,000 marginal CPA.
Why do ad platforms report more conversions than new patients?
View-through conversions, especially on Meta and DSPs, and search conversions that followed earlier impressions can inflate platform totals. Cardinal suggests fitting attribution windows to the business and counting view-throughs as assists.
What measurement model does Cardinal recommend?
Triangulation: last-click attribution from a CRM source of truth, media mix modeling for modeled channel contribution, and incrementality tests such as geo-lift or holdouts to calibrate the model.