Exploring topic-based language models for effective web information retrieval

The main obstacle for providing focused search is the relative opaqueness of search request—searchers tend to express their complex information needs in only a couple of keywords. Our overall aim is to find out if, and how, topic-based language models can leads to more effective web information retrieval. In this paper we explore retrieval performance of a topic-based model that combines topical models with other language models based on cross-entropy. We first define our topical categories and train our topical models on the .GOV2 corpus by building parsimonious language models. We then test the topic-based model on TREC8 small Web data collection for ad-hoc search. Our experimental results show that the topic-based model outperforms the standard language model and parsimonious model.