1. A method for training a ranking application to rank a plurality of help postings for display in a forum, comprising: ranking the plurality of help postings to create an initial ranking, wherein the plurality of help postings in the initial ranking are ranked by the ranking application using initial parameter values; displaying the plurality of help postings in the forum according to the initial ranking; storing user interactions with the plurality of help postings to obtain stored interactions; performing simulations using the stored interactions to generate revised parameter values for the ranking application, wherein performing the simulations comprises: calculating a plurality of relevance values from the stored interactions; creating a test posting; assigning, to the test posting, an initial score and a relevance value randomly selected from the plurality of relevance values to generate a test ranking; determining a probability that a user will view the plurality of help postings and the test posting in the test ranking; generating, based on the probability, simulated rankings of the plurality of help postings and the test posting; and analyzing the simulated rankings based on the relevance value to obtain revised parameter values; and ranking, by the ranking application using the revised parameter values, the plurality of help postings to generate a revised ranking; and displaying the plurality of help postings in the forum according to the revised ranking.
3. The method of claim 1 , wherein the determining the probability is performed according to a cascade click model.