Generative AI and OSS market structure: two-date event-study preregistration
This registration specifies, before analysis, a two-date event study extending our study "Generative AI and Market Structure in Open Source Software: Evidence from GitHub Copilot." The original design compares Python (treated by Copilot's October 2021 multi-IDE expansion) with R (no comparable assistant) on 1,351 matched multihoming package pairs. This preregistration extends the panel beyond September 2022 and designates two later treatment dates for the R ecosystem: the release of ChatGPT (November 30, 2022) and RStudio's Copilot integration (version 2023.09, September 2023). The primary outcome is the onset of a top-1% incumbent tilt in newborn R package manifests, defined as a positive coefficient at p<0.05 sustained for two consecutive quarters. Hypotheses H1 to H4, the onset rule, power considerations for the RStudio user segment, and a disclosure of which data have already been observed are stated in the attached document, which is the registered protocol. Deviations will be reported as such.