Most clinical research sites measure advertising performance with a single metric: cost-per-inquiry. This metric is necessary but insufficient for evaluating geotargeting effectiveness. An inquiry from a patient 40 miles away costs the same as an inquiry from a patient 8 miles away — but produces enrolled patients at a fraction of the rate. Geotargeting performance requires a five-metric framework that follows the patient from ad impression to protocol completion, not just to form submission.
Metric 1: Cost-Per-Inquiry by Geographic Zone
Segment your inquiry data by the patient’s ZIP code (captured on intake form) and calculate cost-per-inquiry separately for each geographic zone: inner radius (0–10 miles), middle (10–20 miles), and outer (20+ miles). A well-configured geotargeting campaign shows roughly equal cost-per-inquiry across zones — if outer zone inquiries cost 50% more, your bid adjustments need recalibration downward for those zones.
Metric 2: Inquiry-to-Screened Rate by Distance Band
Track what percentage of inquiries from each distance band convert to a scheduled and attended screening visit. This is the first metric where distance impact becomes visible. A site with equal cost-per-inquiry across zones but a 55% inquiry-to-screened rate in the inner zone and 28% in the outer zone is paying twice the cost-per-screened-patient from distant advertising. This metric tells you where geographic waste is hiding downstream of the inquiry stage.
Metric 3: Screen-to-Enrolled Rate by Distance Band
Of patients who complete a screening visit, what percentage enroll — by distance band? This captures the second dropout point where distance reveals itself: patients who attend screening but decline to enroll after learning the full visit schedule. This decision is often distance-driven.
Metric 4: Protocol Completion Rate by Distance Band
The ultimate geotargeting metric: of enrolled patients by zone, what percentage complete the protocol? This is tracked at the study level, not at the advertising level, but it is the definitive measure of whether your geographic targeting is capturing the right patients. Target completion rate variance between zones of less than 10 percentage points. Greater variance indicates misaligned geographic targeting.
Metric 5: Cost-Per-Enrolled Patient by ZIP Code
The summary metric. Divide total ad spend attributable to each ZIP code cluster by the number of patients from that cluster who enrolled. This is your geographic ROI map. ZIP codes with cost-per-enrolled below your site average get increased bids. ZIP codes above your site average get reduced bids or exclusion. Run this analysis quarterly and adjust bid modifiers accordingly.
Building the Tracking Infrastructure
To measure these five metrics, you need: (1) a “ZIP code” field on your inquiry form, (2) a lead source tracking system that carries the ZIP code through from inquiry to screen to enroll, and (3) a spreadsheet or dashboard that links ad spend by geographic zone to patient outcomes by geographic zone. Most CRMs and study management systems can export this data; the analysis is typically done in a spreadsheet rather than requiring specialized software.
48-Hour Action List
- Hour 1: Add a required “ZIP code” field to your patient inquiry form if not already present. This single change enables geographic outcome tracking going forward.
- Hour 2: Build a Google Sheet with five tabs — one per metric above. In the first tab, enter your last 90 days of inquiry data segmented by distance band. Calculate metric 1 (cost-per-inquiry by zone) from your ad spend data and inquiry ZIP codes.
- Hour 3: In Google Ads → Reports → Custom reports → add “Distance” as a dimension and “Conversions,” “Cost,” and “Click” as metrics. This gives you metrics 1 and 2 directly from the platform.
- Day 2: Calculate metrics 3, 4, and 5 from your study management system data. Identify your highest and lowest performing ZIP clusters. Adjust bid modifiers in Google Ads to reflect the performance difference.