title: A comparative study of improvements Pre-filter methods bring on feature selection using microarray data.
abstract: BACKGROUND
  Feature selection techniques have become an apparent need in biomarker discoveries with the development of microarray. However, the high dimensional nature of microarray made feature selection become time-consuming. To overcome such difficulties, filter data according to the background knowledge before applying feature selection techniques has become a hot topic in microarray analysis. Different methods may affect final results greatly, thus it is important to evaluate these pre-filter methods in a system way.
  
  
  METHODS
  In this paper, we compared the performance of statistical-based, biological-based pre-filter methods and the combination of them on microRNA-mRNA parallel expression profiles using L1 logistic regression as feature selection techniques. Four types of data were built for both microRNA and mRNA expression profiles.
  
  
  RESULTS
  Results showed that pre-filter methods could reduce the number of features greatly for both mRNA and microRNA expression datasets. The features selected after pre-filter procedures were shown to be significant in biological levels such as biology process and microRNA functions. Analyses of classification performance based on precision showed the pre-filter methods were necessary when the number of raw features was much bigger than that of samples. All the computing time was greatly shortened after pre-filter procedures.
  
  
  CONCLUSIONS
  With similar or better classification improvements, less but biological significant features, pre-filter-based feature selection should be taken into consideration if researchers need fast results when facing complex computing problems in bioinformatics.
authors.affiliation: Research Center for Biomedical Information, Shenzhen Institutes of Advanced Technologies, Chinese Academy of Sciences, Shenzhen, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Research Center for Biomedical Information, Shenzhen Institutes of Advanced Technologies, Chinese Academy of Sciences, Shenzhen, China.
authors.forename: Xiaomao
authors.initials: X
authors.lastname: Fan
authors.affiliation: Research Center for Biomedical Information, Shenzhen Institutes of Advanced Technologies, Chinese Academy of Sciences, Shenzhen, China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Cai
keywords: Comparative study; Feature selection; Microarray
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