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Activity Number: 635 - Advances in Machine Learning
Type: Contributed
Date/Time: Thursday, August 2, 2018 : 8:30 AM to 10:20 AM
Sponsor: Section on Statistical Learning and Data Science
Abstract #330524 Presentation
Title: Assessment of Case Influence in Support Vector Machine
Author(s): Shanshan Tu* and Yoonkyung Lee and Yunzhang Zhu
Companies: The Ohio State University and Ohio State University and The Ohio State University
Keywords: case influence; data perturbation; model diagnostics; path-following algorithm; SVM

Support vector machine (SVM) is a very popular technique for classification. A key property of SVM is that its discriminant function depends only on a subset of data points called support vectors. This comes from the representation of the discriminant function as a linear combination of kernel functions associated with individual cases. Despite the direct relation between each case and the corresponding coefficient in the representation, the influence of cases and outliers on the classification rule has not been examined formally. Borrowing ideas from regression diagnostics, we define case influence measures for SVM and study how the classification rule changes as each case is perturbed. To measure case sensitivity, we introduce a weight parameter for each case and reduce the weight from one to zero to link the full data solution to the leave-one-out solution. We develop an efficient algorithm to generate case-weight adjusted solution paths for SVM. The solution paths and the resulting case influence graphs allow us to look at the relation between individual coefficients and their influences comprehensively. We present numerical results to illustrate the benefit of this approach.

Authors who are presenting talks have a * after their name.

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