Platform Dependency Index (PDI)
PDIConcentration of Allocative Access Across External Platforms
PDI measures concentration of allocative access across external platforms and AI intermediaries.
Definition
PDI quantifies the degree to which an entity depends on a small number of platforms or AI intermediaries for allocative access. Higher PDI indicates greater concentration risk and platform lock-in.
PDI uses concentration metrics to assess how dependent an entity is on specific platforms or AI systems for allocative access. Higher PDI indicates greater lock-in and switching costs.
Conceptual Formula
PDI(e) = 1 - H(normalized_allocative_shares), where H=Herfindahl-Hirschman Index of allocative access across platforms.What This Index Measures
PDI captures allocative platform concentration.
By definition: PDI increases as allocative access concentrates across fewer platforms.
Implications
- High PDI indicates platform lock-in and allocative vulnerability
Methodology
Type
index construction
Data Sources
Confidence Level
medium
Description
PDI(e) = 1 - H(normalized_allocative_shares), where H=Herfindahl-Hirschman Index of allocative access across platforms.
Limitations
- Requires platform-level attribution data
- AI intermediaries may be opaque
Key Takeaways
Key Points
- PDI scales 0-1
- Based on allocative share concentration
- Indicator of platform lock-in risk
Target Audience
Relevance Tags
Source Paper
Citation
For the Platform Dependency Index (PDI), see HomeSelf Research (2026), The Zero-Click Economy.