Signal definition
Framework Migration
The dominant signal type observed: 75% of VC-backed startup GitHub signals are framework migrations, not new features. Counter-narrative to 'engineering velocity = hiring', the dominant pattern is rewrites.
Unit: binary signal (fires / does not fire) · Window: Per commit
Formula
fires if a single PR removes >15% of source files in old-framework directory AND adds >15% in new-framework directory within the same diffDecision rule
Classified as high-confidence framework migration when paired with package.json / pyproject.toml dependency rotation in the same PR.
Common pitfall
Some monorepo cleanups look like framework migrations to a heuristic (mass file moves between directories). We require the dependency-rotation co-occurrence to suppress false positives.
Empirical findings about framework migration
Related signals
Defined in the SSRN-indexed methodology paper. Full definition, assumptions, and validation in §3 of the paper. Reproducibility kit at /reproducibility. Glossary entry at /glossary#framework-migration.
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