I did asked this question in class:
Stable state (hub value zero) and probability of spending more time in particular web page will be the factors to estimate page rank. Though, link analysis can estimate which pages are expected to be most visited, it is not easy to know how much time a user spends at any particular page.
One simple method I can think of is by analyzing how often (considering time gap) a user selects alternative links proposed by search engines after selecting one.
--bhaskar
