The Hanover Collaboration

I think I’ve got Netflix pretty well trained to give me good movies. Of course this is largely a good job on their part; but I think that I had something to do with it.

I only rate 5s and 1s. Everything in between I don’t rate.

I’m pretty sure that Netflix still uses quadratic loss when predicting your ratings. I think this is really holding them back since it puts an artificial central pressure on ratings. I’m also suspicious that there is a thresholding effect at 4 stars. Specifically, for clustering purposes, I think considers 4 and 5 stars to be the same thing, “movies you liked”. It finds other people who have a high intersection of 4—5 movies and uses them as predictors.

Early on, I rated X-men 3 at the 4 level which led to systematic over-prediction of franchise action movies. That was a mistake. I fixed that by downgrading it to 3 but then putting a 5 on X-Men 1.

Every time I see a bad movie, I make sure to tell Netflix, especially if everyone else rated it highly, e.g., Million Dollar Baby.