The Impact of Frequency on Summarization

Most multi-document summarizers utilize term frequency related features to determine sentence importance. No empirical studies, however, have been carried out to isolate the contribution made by frequency information from that of other features. Here, we examine the impact of frequency on various aspects of summarization and the role of frequency in the design of a summarization system. We describe SumBasic, a summarization system that exploits frequency exclusively to create summaries. SumBasic outperforms many of the summarization systems in DUC 2004, and performs very well in the 2005 MSE evaluation, confirming that frequency alone is a powerful feature in summary creation. We also demonstrate how a frequency-based summarizer can incorporate context adjustment in a natural way, and show that this adjustment contributes to the good performance of the summarizer and is sufficient means for duplication removal in multi-document summarization.