[samplenoise]

I don’t remember if the paper lists it among its limitations but it’s worth noting there is a pretty sharp continuity in Billboard’s methodology around 1991 (they didn’t really include any rap before that) that will warp this kind of analysis if you don’t control for it. This is sort of known among musicologists of pop music and often glossed over by this kind of research

[contravariant]

Did you mean 'discontinuity'? Sharp and continuous are somewhat contradictory.