  Neural code synthesis has reached a point where snippet generation is
accurate enough to be considered for integration into human software
development workflows. Commercial products aim to increase programmers'
productivity, without being able to measure it directly. In this case study, we
asked users of GitHub Copilot about its impact on their productivity, and
sought to find a reflection of their perception in directly measurable user
data. We find that the rate with which shown suggestions are accepted, rather
than more specific metrics regarding the persistence of completions in the code
over time, drives developers' perception of productivity.
