There are a number of approaches to this with increasing complexity: - Sum of votes divided by total votes - More advanced statistical algorithms that take in

There are a number of approaches to this with increasing complexity: - Sum of votes divided by total votes - More advanced statistical algorithms that take into account confidence (as this article suggests) - Recommendation engines that provides a rating based on your taste profile But I'm pretty sure you could take this further depending on what data you're looking to feed in and what the end-users' expectations of the system are.