Efficiently determining the probability of a user clicking a hyperlink

Question

So I have a bunch of hyperlinks on a web page. From past observation I know the probabilities that a user will click on each of these hyperlinks. I can therefore calculate

Answer 1

You need to know how strongly X is correlated with W.

Most likely you also want to have a more complex mathematical model if you want to develop a big website. If you run a website like digg you have a lot of prior knowledge that you have to factor into your calcualtion. That leads to multivariate statistics.