My central research interest is information retrieval – studying representations of information needs and documents in the context of models of relevance. This is the basis of search engines, which are an essential tool for all researchers. One focus of my group is social media such as forums and blogs. We are studying how to search large collections of this type of data, understand the role of conversations, and characterize the topics of conversations on a given topic. Opinion and sentiment analysis is an important topic for many applications related to CSS, and we are working on various aspects of this problem, such as quantifying the diversity and importance of opinions in a ranked list of social posts.