1. A method comprising: using at least one computer processor, extracting from a web log information comprising web-page events; identifying from the web-page events a web page that is included in a trail of web pages, which guide browsing sessions to conversions on a plurality of browsed-to web pages that are browsed to after the web page; calculating a first entropy that quantifies an amount of conversion uncertainty in the trail of web pages before the one or more browsing sessions navigate to the web page; calculating a second entropy that quantifies an amount of conversion uncertainty in the trail of web pages after the one or more browsing sessions navigate to the web page; and computing an information gain from the first entropy to the second entropy, wherein the information gain suggests whether a significant conversion disparity exists among the plurality of browsed-to web pages.