[jon_richards]

One complaint I've heard is people looking for restaurants and finding 4-5 star rated McDonalds. Seems ripe for PCA or something. There are a ton of examples of this sort of analysis too, especially since Netflix made their datasets available. Here's the first paper I found: http://www.lkozma.net/mlsp09binary.pdf

[chrisfosterelli]

I think absolute ratings for restaurants in general tend to be garbage, since a rating is skewed to the average expectations of the guests.

The 5-star McDonalds may be a really good McDonalds that's very clean and consistent, but the $50/meal ocean-side bar only has 3-stars because the steak is sometimes rare instead of medium-rare. People are rating relative to their expectations of the restaurant, so someone who doesn't share those same expectations will be confused that a dollar cheese burger is 5 stars but a prime rib steak is 3 stars.

[jon_richards]

Yeah, that's why I recommend PCA. It works by finding groups of agreement. You can then classify people by how much they resemble each group and predict how they will react to a new thing by how their groups have reacted to it. One criticism is that using it can easily lead to constructing echo chambers, but that's exactly what you want for reviews. If you care about how a steak is cooked, here is how other people who care about how a steak is cooked review this restaurant.