Project
This page uses the design-structure logic from your methods work and applies it to CT.gov architecture fields: how many arms and interventions a trial declares, and what that predicts about visibility.
One-arm and one-intervention studies are not cleaner registry citizens. They are often the quietest.
A standalone E156 project on how arm count and intervention count map onto older-study hiddenness in CT.gov.
Across The Series
The split projects are meant to be read together because each isolates a different dimension of registry opacity rather than forcing every question into one leaderboard.
Industry-focused missing-results stock, sponsor backlogs, and structural sparsity inside CT.gov.
Sponsor-class comparisons on rate, stock, and structural hiddenness rather than one flattened ranking.
Phase-by-phase disclosure gaps showing how silence changes along the development pathway.
Field-level missingness across publication links, IPD statements, descriptions, and locations.
Results-plus-publication visibility states showing how many older trials are fully visible, partly visible, or ghosted.
Completion-era reporting debt showing how older eligible cohorts drift on no-results and ghost-protocol rates.
Keyword-classified therapeutic-area hiddenness mapping across common condition families.
Concentration and inequality analysis showing how much unresolved stock sits inside a thin sponsor slice.
Policy-era comparisons across pre-FDAAA, FDAAA, and later CT.gov completion cohorts.
Sample-based external PubMed NCT audit testing how often CT.gov no-link records hide an external paper trail.
Oncology-specific CT.gov hiddenness showing where cancer-trial stock, phases, and sponsors still go quiet.
Cardiovascular CT.gov hiddenness showing how heart and vascular studies remain quiet across major phases and sponsors.
Metabolic CT.gov hiddenness across obesity, diabetes, and related trial portfolios with large late-phase and NA stock.
Enrollment-size gradients showing how older small trials remain much quieter than larger registered studies.
Site and country footprint analysis showing how larger trial geographies map onto much better public visibility.
Primary-purpose and allocation analysis showing which trial intents remain most obscured on CT.gov.
Registration-to-completion delay analysis showing short-cycle studies carry the heaviest reporting debt.