BEHAVIORAL FILTER FOR PERSONALIZED RECOMMENDATIONS BASED ON BEHAVIOR AT THIRD-PARTY CONTENT SITES

This disclosure relates to selectively filtering seed behavior, e.g., user activity used to generate item recommendations, based on the availability of item classifications. Seed behaviors and catalog items may be associated with categories in an electronic catalog, and a particular seed behavior may be used to generate user recommendations if it is more recent than a user's last purchase in the category of the seed behavior. For example, a user's activity in the TV category, e.g., viewing various TV models, may not be used to generate recommendations if the activity occurred prior to the user's purchase of a TV. As a result, additional TVs may not appear in the user's recommendations following the purchase of a TV. However, if classification information is unavailable relating to the purchase, seed behavior may be filtered across a set of categories, not just the TV category to reduce the chance of less effective recommendations.