Categorical (topic) similarity between a web page and an advertisement (ad) text has long been used for contextual advertising. In this paper, we explore the use of the categorical similarity score, referred to as Category Match Score (CMS), in the context of search advertising. In particular, we explore the effect of CMS on various ad-effectiveness prediction tasks, including user-judgment prediction, ad click-through-rate prediction (CTR), and revenue-per-impression prediction. Our extensive experiments on two editorial datasets and one live traffic dataset demonstrate that CMS is one of the strongest features in the judgment prediction task and that CMS-based filtering is very effective in improving revenue per impression as well as CTR. We believe that our analyses can be extremely effective in helping web service providers serve more relevant and profitable ads to users.

Topic models are used to group words in a text dataset into a set of relevant topics. Unfortunately, when a few words frequently appear in a dataset, the topic groups identified by topic models become noisy because these frequent words repeatedly appear in "irrelevant" topic groups. This noise has not been a serious problem in a text dataset because the frequent words (e.g., the and is) do not have much meaning and have been simply removed before a topic model analysis. However, in a social network dataset we are interested in, they correspond to popular persons (e.g., Barack Obama and Justin Bieber) and cannot be simply removed because most people are interested in them.

In this paper, we discuss how we can extend probabilistic topic models to analyze the relationship graph of popular social-network data, so that we can group or label the edges and nodes in the graph based on their topic similarity. In particular, we first apply the well-known Latent Dirichlet Allocation (LDA) model and its existing variants to the graph-labeling task and argue that the existing models do not handle popular nodes (nodes with many incoming edges) in the graph very well. We then propose possible extensions to this model to deal with popular nodes. Our experiments show that the proposed extensions are very effective in labeling popular nodes, showing significant improvements over the existing methods. Our proposed methods can be used for providing, for instance, more relevant friend recommendations within a social network.