Chi-square-based Scoring Function for Categorization of MEDLINE Citations

A. Kastrin; B. Peterlin; D. Hristovski

doi:10.3414/ME09-01-0009

Methods of Information in Medicine, Table of Contents

Methods Inf Med 2010; 49(04): 371-378
DOI: 10.3414/ME09-01-0009

Original Articles

Schattauer GmbH

Chi-square-based Scoring Function for Categorization of MEDLINE Citations

Authors

A. Kastrin

¹Institute of Medical Genetics, University Medical Centre Ljubljana, Ljubljana, Slovenia
B. Peterlin

¹Institute of Medical Genetics, University Medical Centre Ljubljana, Ljubljana, Slovenia
D. Hristovski

²Institute for Biostatistics and Medical Informatics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia

Abstract

Summary

Objectives: Text categorization has been used in biomedical informatics for identifying documents containing relevant topics of interest. We developed a simple method that uses a chi-square-based scoring function to determine the likelihood of MEDLINE^® citations containing genetic relevant topic.

Methods: Our procedure requires construction of a genetic and a nongenetic domain document corpus. We used MeSH^® descriptors assigned to MEDLINE citations for this categorization task. We compared frequencies of MeSH descriptors between two corpora applying chi-square test. A MeSH descriptor was considered to be a positive indicator if its relative observed frequency in the genetic domain corpus was greater than its relative observed frequency in the nongenetic domain corpus. The output of the proposed method is a list of scores for all the citations, with the highest score given to those citations containing MeSH descriptors typical for the genetic domain.

Results: Validation was done on a set of 734 manually annotated MEDLINE citations. It achieved predictive accuracy of 0.87 with 0.69 recall and 0.64 precision. We evaluated the method by comparing it to three machine-learning algorithms (support vector machines, decision trees, naïve Bayes). Although the differences were not statistically significantly different, results showed that our chi-square scoring performs as good as compared machine-learning algorithms.

Conclusions: We suggest that the chi-square scoring is an effective solution to help categorize MEDLINE citations. The algorithm is implemented in the BITOLA literature-based discovery support system as a preprocessor for gene symbol disambiguation process.

Keywords

Applied statistics - text mining - natural language processing - document categorization

Full Text

References

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