Selection Of Expansion Terms Research Articles

On the query reformulation technique for effective MEDLINE document retrieval

Improving the retrieval accuracy of MEDLINE documents is still a challenging issue due to low retrieval precision. Focusing on a query expansion technique based on pseudo-relevance feedback (PRF), this paper addresses the problem by systematically examining the effects of expansion term selection and adjustment of the term weights of the expanded query using a set of MEDLINE test documents called OHSUMED. Implementing a baseline information retrieval system based on the Okapi BM25 retrieval model, we compared six well-known term ranking algorithms for useful expansion term selection and then compared traditional term reweighting algorithms with our new variant of the standard Rocchio’s feedback formula, which adopts a group-based weighting scheme. Our experimental results on the OHSUMED test collection showed a maximum improvement of 20.2% and 20.4% for mean average precision and recall measures over unexpanded queries when terms were expanded using a co-occurrence analysis-based term ranking algorithm in conjunction with our term reweighting algorithm ( p-value < 0.05). Our study shows the behaviors of different query reformulation techniques that can be utilized for more effective MEDLINE document retrieval.

Clinical task-specific query expansion for the retrieval of scientifically rigorous research documents.

To support the practice of evidence-based medicine (EBM), clinically relevant and scientifically sound articles should be easily accessible. Due to the huge volume of medical literature and the low performance of present retrieval models, clinicians could only get relevant documents in the order of publication time. This study propose a new clinical task-specific retrieval technique that improves retrieval accuracy by exploiting clinical task-specific EBM terms to query expansion using co-occurrence analysis technique. The idea is aimed at selecting query expansion terms that are relevant to a specific clinical-task using task-specific EBM terms. Focusing on treatment and diagnosis tasks, the new method which was performed on the OHSUMED collection showed a further improved result than the existing method.

Query expansion behavior within a thesaurus‐enhanced search environment: A user‐centered evaluation

AbstractThe study reported here investigated the query expansion behavior of end‐users interacting with a thesaurus‐enhanced search system on the Web. Two groups, namely academic staff and postgraduate students, were recruited into this study. Data were collected from 90 searches performed by 30 users using the OVID interface to the CAB abstracts database. Data‐gathering techniques included questionnaires, screen capturing software, and interviews. The results presented here relate to issues of search‐topic and search‐term characteristics, number and types of expanded queries, usefulness of thesaurus terms, and behavioral differences between academic staff and postgraduate students in their interaction. The key conclusions drawn were that (a) academic staff chose more narrow and synonymous terms than did postgraduate students, who generally selected broader and related terms; (b) topic complexity affected users' interaction with the thesaurus in that complex topics required more query expansion and search term selection; (c) users' prior topic‐search experience appeared to have a significant effect on their selection and evaluation of thesaurus terms; (d) in 50% of the searches where additional terms were suggested from the thesaurus, users stated that they had not been aware of the terms at the beginning of the search; this observation was particularly noticeable in the case of postgraduate students.