The authors make this conclusion:

What we have demonstrated in this study is that given access to adequate program notes, it is possible to extract statistics which give a measure of productivity in the performing arts. Our conclusion is that Baumol's Disease does seem to afflict the performing arts, but that its pathology is more complex than its discoverers originally supposed it to be! The limiting factor is not the technology of the performance so much as the size of auditoria and what people will pay to go into them.

What we have demonstrated in this study is that given access to adequate program notes, it is possible to extract statistics which give a measure of productivity in the performing arts.