An Improved Classifier Chain Ensemble for Multi-DimensionalClassification with Conditional Dependence

• Main Author: Heydorn, Joseph Ethan
• Format: Others
• Published: BYU ScholarsArchive 2015
• Subjects: multi-dimensional classification; multi-target; conditional dependence; ensemble; chain classifier; Computer Sciences
• Online Access: https://scholarsarchive.byu.edu/etd/5515; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=6514&context=etd

We focus on multi-dimensional classification (MDC) problems with conditional dependence, which we call multiple output dependence (MOD) problems. MDC is the task of predicting a vector of categorical outputs for each input. Conditional dependence in MDC means that the choice for one output value affects the choice for others, so it is not desirable to predict outputs independently. We show that conditional dependence in MDC implies that a single input can map to multiple correct output vectors. This means it is desirable to find multiple correct output vectors per input. Current solutions for MOD problems are not sufficient because they predict only one of the correct output vectors per input, ignoring all others.We modify four existing MDC solutions, including chain classifiers, to predict multiple output vectors. We further create a novel ensemble technique named weighted output vector ensemble (WOVE) which combines these multiple predictions from multiple chain classifiers in a way that preserves the integrity of output vectors and thus preserves conditional dependence among outputs. We verify the effectiveness of WOVE by comparing it against 7 other solutions on a variety of data sets and find that it shows significant gains over existing methods.