MedEval - A Swedish medical test collection with doctors and patients user groups

Test collections for information retrieval are scarce. Domain specific test collections even more so, and medical test collections in the Swedish language non-existent prior to the making of the MedEval test collection. Most research in information retrieval has been performed in the English language, thus most test collections contain English documents. However, English is morphologically poor compared to many other European languages and a number of interesting and important aspects have not been investigated. Building a medical test collection in Swedish opens new research opportunities.

This article describes the making of and potential uses of MedEval, a Swedish medical test collection with assessments, not only for topical relevance, but also for target reader group: Doctors or Patients. A user of the test collection may choose if she wishes to search in the Doctors or the Patients scenario where the topical relevance assessments have been adjusted with consideration to user group, or to search in a scenario which regards only topical relevance.In addition to having three user groups, MedEval, in its present form, has two indexes, one where the terms are lemmatized and one where the terms are lemmatized and the compounds split and the constituents indexed together with the whole compound.

Differences discovered between the documents written for medical professionals and documents written for laypersons are presented. These differences may be utilized in further studies of retrieval of documents aimed at certain groups of readers. Differences between the groups of documents are, for example, that professional documents have a higher ratio of compounds, have a greater average word length and contain more multi-word expressions.An experiment is described where the user scenarios have been utilized, searching with expert terms and lay terms, separately and in combination in the different scenarios. The tendency discovered is that the medical expert gets best results using expert terms and the lay person best results using lay terms, but also quite good results using expert terms or lay and expert terms in combination.

The many features of MedEval gives a variety of research possibilities, such as comparing the effectiveness of search terms when it comes to retrieving documents aimed at the different user groups or to study the effect of compound decomposition in retrieval of documents. As Swedish, the language of MedEval, is a morphologically more complex language than English, it is possible to study additional aspects of the effect of natural language processing in information retrieval, for example utilizing different inflectional word forms in the retrieval of expert vs lay documents. MedEval is the first Swedish test collection of the medical domain.

The Department of Swedish at the University of Gothenburg is in the process of making the MedEval test collection available to academic researchers.