If you're interested in a more rigorous analysis of the problem, I highly recommend reading the paper "How to Count Thumb-Ups and Thumb-Downs: User-Rating based

If you're interested in a more rigorous analysis of the problem, I highly recommend reading the paper "How to Count Thumb-Ups and Thumb-Downs: User-Rating based Ranking of Items from an Axiomatic Perspective": http://www.dcs.bbk.ac.uk/~dell/publications/dellzhang_ictir2011.pdf http://www.dcs.bbk.ac.uk/~dell/publications/dellzhang_ictir2... It's very accessible for an academic paper.