[nickcano]

They could have used PCA[1] on their feature set and let a human come up with these; they claim to use machine learning, not that this checklist was generated as a result of machine learning.

Otherwise, maybe they have an algorithm that looked at resulting classifications from learning and flagged inputs with the largest and most consistent variance across classes.

[1]https://en.wikipedia.org/wiki/Principal_component_analysis

[cheez]

I'm OK with a human being involved, I'm curious how they actually figured it out.