If we studied folks with _no_ AI experience, then we might underestimate speedup, as these folks are learning tools (see a discussion of learning effects in section (C.2.7) - Below-average use of AI tools - in the paper). If we studied folks with _only_ AI experience, then we might overestimate speedup, as perhaps these folks can't really program without AI at all.
In some sense, these are just two separate and interesting questions - I'm excited for future work to really dig in on both!
Wouldn't this be an underestimate, since without ai there'd be no forward progress at all? So ai-assisted is infinite speedup if the outputs are good.