Tom McGrath says that after finding structure with a supervised method, an unsupervised method can help reveal unexpected structure and estimate how much structure exists.

“or just a line really um and so this was sort of enough to show that this exists and then the question is like you know i i think whenever you have a supervised method you often want to try and find an unsupervised way of doing the same thing um you know because that lets you answer the question not only does it exist but like what else is there that we might not have expected and how much is there”