Towards Improving Search Results for Medical Experts and Laypersons.

In a domain such as medicine, it is important that individualsu0027 infor- mation needs are met with information on a suitable level of difficulty and ex- pertise. 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 re- sult 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 que- ry reformulation and document length, average word length or compound ratio for re-ranking. The Swedish medical IR test collection, MedEval, from Sprakbanken, Uni- versity of Gothenburg, will be used to find features specific for professional language and lay language and to study the effectiveness of these features in re- formulating 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 for- mat, except patient records. The collection contains 62 topics. In total, 7,044 documents have been assessed both for relevance to these topics and for tar- get group. Our experiments will be based on earlier explorative studies on medical ex- pert 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 individ- ual MWUs were much higher in the expert documents. For the doctors, medical phrases dominate the MWUs while the patientsu0027 documents mostly contained general language units. The most frequent patient MWUs from the medical do- main, 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 indicat- ing 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 reformu- late queries and that the likewise typical features can be useful for calculating