What is Extrinsic Evaluation

As more information becomes available online, information-overloading results. This problem can be resolved through the application of automatic summarization. Traditional summarization models consider a document as a sequence of sentences. Actually, a large document has a well-defined hierarchical structure. Human abstractors use the hierarchical structure of the document to extract topic sentences. They start searching for topic sentences from the top level of the document structure downwards. Similarly, hierarchical summarization generates a summary for a document based on the hierarchical structure and salient features of the document. User evaluations that have been conducted indicate that hierarchical summarization outperforms traditional summarization.