CT.gov Enrollment-Size Gap
2026-03-29 | full-registry ct.gov audit | plots, figures, and e156 bundle
Series
IndustrySponsor ClassesPhasesStructuralVisibilityCohortsConditionsConcentrationRule ErasPubMed AuditOncologyCardiovascularMetabolicSizeGeographyPurposeDelayArchitecture
Enrollment Dashboard

Visibility improves with trial scale, but large size does not erase every sponsor backlog

Recorded enrollment size is a strong visibility gradient in CT.gov, yet large OTHER-sponsored studies remain heavily obscured despite scale.

Open dashboardRead E156 paperProtocolSeries hub
No results
Ghosts
Treatment only
Sponsor contrast

Dashboard

Open dashboard at rootRead E156 micro-paperOpen protocolOpen series hub

Enrollment size is one of the clearest structural gradients in the registry once older studies are isolated.

How to read the dashboard
1-50 no results
73.2%
Small-study bucket
1001-5000 ghosts
18.7%
Large-study ghost rate
Treatment 1-50
69.6%
Treatment-only small bucket
Treatment 1001-5000
48.0%
Treatment-only large bucket
No-results by size
ENROLLMENT-SIZE BUCKETS2-year no-results rate by recorded enrollment size1-5073.2%51-10075.7%101-50067.3%501-100057.1%1001-500062.4%5001+68.8%
Older studies get materially quieter as recorded enrollment falls.
This is the public-facing version of a scale gradient: the smallest studies carry the heaviest reporting debt.
Ghost protocols by size
GHOST-PROTOCOL RATESShare of older studies with neither results nor publication by size bucket1-5047.6%51-10042.8%101-50032.0%501-100021.7%1001-500018.7%5001+18.7%
The ghost-protocol gradient is steeper than the no-results gradient and collapses among larger studies.
Publication-only visibility explains some of the gap, but the combined ghost metric keeps the hidden zone visible.
Treatment and sponsor contrast
WITHIN-BUCKET CONTRASTLarge-size treatment and sponsor-class contrasts inside the size gradientTreatment | 1-5069.6%Treatment | 1001-500048.0%INDUSTRY | 1001-500031.6%OTHER | 1001-500081.5%
The size effect remains within treatment trials, but large OTHER-sponsored studies still look far worse than large industry studies.
This panel matters because pure size could otherwise be mistaken for a sponsor-mix artifact.
Read Across Projects

Across The Series

Each project isolates a different dimension of registry opacity, but the point is the contrast between them, not a single leaderboard.

Industry
CT.gov Industry Disclosure Gap

Industry-focused missing-results stock, sponsor backlogs, and structural sparsity inside CT.gov.

Sponsor Classes
CT.gov Sponsor-Class Hiddenness

Sponsor-class comparisons on rate, stock, and structural hiddenness rather than one flattened ranking.

Phases
CT.gov Phase Reporting Gap

Phase-by-phase disclosure gaps showing how silence changes along the development pathway.

Structural
CT.gov Structural Missingness

Field-level missingness across publication links, IPD statements, descriptions, and locations.

Visibility
CT.gov Evidence Visibility Gap

Results-plus-publication visibility states showing how many older trials are fully visible, partly visible, or ghosted.

Cohorts
CT.gov Completion Cohort Debt

Completion-era reporting debt showing how older eligible cohorts drift on no-results and ghost-protocol rates.

Conditions
CT.gov Condition Hiddenness Map

Keyword-classified therapeutic-area hiddenness mapping across common condition families.

Concentration
CT.gov Sponsor Backlog Concentration

Concentration and inequality analysis showing how much unresolved stock sits inside a thin sponsor slice.

Rule Eras
CT.gov Rule-Era Reporting Gap

Policy-era comparisons across pre-FDAAA, FDAAA, and later CT.gov completion cohorts.

PubMed Audit
CT.gov Publication Undercount Audit

Sample-based external PubMed NCT audit testing how often CT.gov no-link records hide an external paper trail.

Oncology
CT.gov Oncology Hiddenness

Oncology-specific CT.gov hiddenness showing where cancer-trial stock, phases, and sponsors still go quiet.

Cardiovascular
CT.gov Cardiovascular Hiddenness

Cardiovascular CT.gov hiddenness showing how heart and vascular studies remain quiet across major phases and sponsors.

Metabolic
CT.gov Metabolic Hiddenness

Metabolic CT.gov hiddenness across obesity, diabetes, and related trial portfolios with large late-phase and NA stock.

Geography
CT.gov Geography-Scale Visibility

Site and country footprint analysis showing how larger trial geographies map onto much better public visibility.

Purpose
CT.gov Design-Purpose Hiddenness

Primary-purpose and allocation analysis showing which trial intents remain most obscured on CT.gov.

Delay
CT.gov Completion-Delay Debt

Registration-to-completion delay analysis showing short-cycle studies carry the heaviest reporting debt.

Architecture
CT.gov Trial-Architecture Gap

Arm-count and intervention-count analysis showing simpler trial architectures are often the quietest.

Source on GitHub | Project home | Dashboard