Measuring the disorder and evenness of trial distribution across geography.
Africa Cities/Trial
80
Europe Cities/Trial
Lower
Model
Spatial entropy
Trials Audited
1,000
Key Finding
Africa's normalised entropy was 0.49, meaning the continent uses only half its maximum possible geographic diversity for trial placement.
Regional Comparison
Hiv — Condition Analysis
Multi-Dimensional Equity Profile
Design Feature & Temporal Trend
Inequality Decomposition & Statistics
Hiv — Computed Statistics
Africa: 1,793 | US: 5,071 | Europe: 1,451 | Ratio: 2.8x
Africa share: 21.6% | HHI4-region = 0.449 | Shannon H = 1.47 bits
Open Label: AF 1,545 vs US 23,963 (15.5x gap)
Ginicountry = 0.857 [0.61, 0.90] | αpower-law = 1.40 | Atkinson A(2) = 0.979
KL(obs||uniform) = 2.93 bits | ρSpearman(pop, trials/M) = −0.01
Why It Matters
Africa shows paradoxically high city-density per trial — not because access is widespread, but because multi-site Phase 3 validation studies are designed to recruit rapidly across many locations. Europe's lower city-density reflects focused, specialised research at established centres. Africa provides geographic breadth for enrollment; Europe provides scientific depth for discovery.
The Evidence 150 words · target 156
In information theory applied to clinical research, does the Shannon entropy of trial site distribution reveal differences in geographic diversity between African and European research ecosystems? This analysis computed Shannon entropy in bits for the distribution of 23,873 African and 142,126 European trials across national units using ClinicalTrials.gov API v2 data. The normalised entropy (H/H_max) served as the primary estimand for distributional evenness, where 1.0 indicates perfect equality across all countries. Africa's normalised entropy was 0.49, meaning the continent uses only half its maximum possible geographic diversity for trial placement. Europe achieved a normalised entropy of 0.82, reflecting substantially more even distribution across its constituent nations. The information-theoretic deficit of 0.33 quantifies the geographic knowledge loss from Africa's concentrated research model. These findings frame research equity as a measurable information-theoretic property rather than a subjective political judgment. Interpretation is limited by the use of national rather than sub-national geographic units.
Sentence Structure
Question
In information theory applied to clinical research, does the Shannon entropy of trial site distribution reveal differences in geographic diversity between African and European research ecosystems?
Dataset
This analysis computed Shannon entropy in bits for the distribution of 23,873 African and 142,126 European trials across national units using ClinicalTrials.gov API v2 data.
Method
The normalised entropy (H/H_max) served as the primary estimand for distributional evenness, where 1.0 indicates perfect equality across all countries.
Primary Result
Africa's normalised entropy was 0.49, meaning the continent uses only half its maximum possible geographic diversity for trial placement.
Robustness
Europe achieved a normalised entropy of 0.82, reflecting substantially more even distribution across its constituent nations.
Interpretation
The information-theoretic deficit of 0.33 quantifies the geographic knowledge loss from Africa's concentrated research model.
Boundary
These findings frame research equity as a measurable information-theoretic property rather than a subjective political judgment.