[nkurz]

I tend to advocate methods that take into account the variance of the belief in order to minimize the risk of showing bad stuff at the top of the heap.

Penalizing variance would be the opposite of my intuition. Given a boring low-variance item with 10 3-star votes, and a divisive item with 5 1-star votes and 5 5-star votes, I'd think you'd want the one at the top to be the one with the medium chance that they'll "love" it than a high chance they'll find it passable.

If you further assume that the average person is going to check out the top few results but only "buy" if they find something they really like, the risky approach seems even more appealing. A list topped by known mediocre choices has a low chance of "success". What's the scenario you are envisioning?

[stdbrouw]

The kind of divisive item you describe is rare, at least on Amazon. What happens most commonly is that everyone loves something or everyone hates it, with some noise (e.g. 10% 1 or 2 star reviews). In this case, it makes sense to promote the item that has a 4.5 mean score and 100 reviews over one that has a 4.7 mean score and only 5 reviews. You want to account for the uncertainty when there are few ratings. If you don't, all the items at the top of your search results will be 5-star 1-review products.