How are movie ratings (stars) calculated?

[Dollar Colonel]

I find the feature helpful in deciding which movies to buy, even though my tastes might not line up completely with the site. Are the ratings a straight calculation of the mean? Or are they weighed in some way?

I would love it if the ratings were weighed to factor in each user's range of scores, so a 10 from someone who gives 10s all the time isn't as important as someone like me who actually uses 5 as an average film and 9 for an amazing film. Or maybe the site can be like old Netflix and guess what rating I would give.

I was curious since Five Feet Apart hasn't come out yet but has a 6.9 rating even though there's only one person who apparently rated it.