I would rather go to a restaurant with a 4.9 rating based on 1000 reviews than to a restaurant with one with a 5 rating based on 1 review. Makes me wonder: how would that feeling translate into a ranking function though.
Thanks for your comment, it made me do my homework. And apologies, I lazily viewed the first dozen rows and assumed that it was a simple high to low sort, and I was wrong. The author used https://en.m.wikipedia.org/wiki/Bayesian_average which answers my question. Cheers.