1. A collaborative filtering method for evaluating a group of items to aid in predicting utility of items for a particular user, comprising: assigning an item value of either known or missing to each item of a group of web data objects; applying a modification scheme to item values of the missing items to assign a confidence value to each of the item values of the missing items, thereby generating a group of modified item values; and evaluating the group of items having modified item values and the group known items to generate a prediction of utility of items for a particular user.