The added value of task and ontology-based markup for information retrieval

In this paper we investigate how retrieving information can be improved through task related indexing of documents based on ontologies. Different index types, varying from content­based keywords to structured task­based indexing ontologies are compared in an experiment that simulates the task of creating instructional material from a database of source material. To be able to judge the added value of task and ontology related indexes, traditional information retrieval performance measures are extended with new measures reflecting the quality of the material produced with the retrieved information. The results of the experiment show that a structured task­based indexing ontology improves the quality of the product created from retrieved material only to some extent, but that it certainly improves the efficiency and effectiveness of search and retrieval and precision of use.