1 vs 1 vote: calculate ratings (Flickchart.com)

Instead of rating items with grades from 1 to 10, I would like to have 1 vs 1 "fights". Two items are displayed beside each other and you pick the one which you like more. Based on these "fight" results, an algorithm should calculate ratings for each item.

You can see this approach on Flickchart.com where movies are rated using this approach.

It looks like this:

As you can see, items are pushed upwards if they win a "fight". The ranking is always changing based on the "fight" results. But this can't be only based on the win quote (here 54%) since it's harder to win against "Titanic" than against "25th Hour" or so.

There are a few things which are quite unclear for me: - How are the ratings calculated? How do you decide which film is on the first place in the ranking? You have to consider how often an items wins and how good are the beaten items. - How to choose which items have a "fight"?

Of course, you can't tell me how Flickchart exactly does this all. But maybe you can tell me how it could be done. Thanks in advance!

This might not be exactly what flickchart is doing, but you could use a variant of the ELO algorithm used in chess (and other sports), since these are essentially fights/games that they win/lose.

Basically, all movies start off with 0 wins/losses and every time they get a win they get a certain amount of points. You usually have an average around 20 (but any number will do) and winning against a movie with the same rating as yourself will give exactly that 20. Winning against a bad movie will maybe give around 10 points, while winning against a better movie might give you 30 points. The other way around, losing to a good movie you only lose 10 points, but if you lose to a bad movie, you lose 30 points.

The specifics of the algorithm is in the wikipedia link.