Towards Improving Search Results for Medical Experts and Laypersons

In a domain such as medicine, it is important that individuals’ information needs are met with information on a suitable level of difficulty and expertise. This paper focuses on facilitating medical information access through reformulating queries and re-ranking result lists utilizing features typical for the language written for professionals or for laypersons. The aim is to produce result lists where the ranking is better suited for the expertise level of the user. We will explore the possibility of using features such as trigger phrases for query reformulation and document length, average word length or compound ratio for re-ranking. The Swedish medical IR test collection, MedEval, from Språkbanken, University of Gothenburg, will be used to find features specific for professional language and lay language and to study the effectiveness of these features in reformulating queries and re-ranking search results based on the target group. The test collection contains 42,250 documents from the medical corpus MedLex , collected from all types of written medical information found in electronic format, except patient records. The collection contains 62 topics. In total, 7,044 documents have been assessed both for relevance to these topics and for target group. Our experiments will be based on earlier explorative studies on medical expert and lay language where some features were identified. It was found that documents written for professionals tended to have more tokens per document, longer words, and more compounds than lay documents The assessed documents were run through a perl program which counted the frequencies of occurring multiword units (MWUs). The frequencies of individual MWUs were much higher in the expert documents. For the doctors, medical phrases dominate the MWUs while the patients’ documents mostly contained general language units. The most frequent patient MWUs from the medical domain, were more frequent in the doctor documents and could therefore not be said to be typical for patient documents. Many frequently recurring MWUs are not specific for any topic. However, they may be seen as trigger phrases indicating target group. Such trigger phrases will be used in the reformulation of the queries. We believe that the phrases typical for a user group can be used to reformulate queries and that the likewise typical features can be useful for calculating target group scores for medical documents and further for improving the ranking of the documents to better match the expertise of the user.