Discordancy tests for outlier detection in multi-item questionnaires
Zijlstra,W.P. van der Ark,L.A. Sijtsma,K.
Zijlstra,W.P.
van der Ark,L.A.
Sijtsma,K.
Abstract
The sensitivity and the specificity of four outlier scores were studied for four different discordancy tests. The outlier scores were the Mahalanobis distance, a robust version of the Mahalanobis distance, and two measures tailored to discrete data, known as O+ and G+. The discordancy tests were Tukey’s fences (a.k.a. boxplot). Tukey’s fences with adjustment for skewness (adjusted boxplot), the generalized extreme studentized deviate (ESD), and the transformed ESD (ESD-T). Outlier scores O+ and G+ performed better than the Mahalanobis distance and its robust version. Discordancy tests ESD-T and adjusted boxplot were advocated for high specificity and ESD for high sensitivity. Keywords: discordancy test, Mahalanobis distance, outlier detection in questionnaire data, outlier score O+, outlier score G+, robust Mahalanobis distance
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Date
2013
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Zijlstra, W P, van der Ark, L A & Sijtsma, K 2013, 'Discordancy tests for outlier detection in multi-item questionnaires', Methodology: European Journal of Research Methods for the Behavioral and Social Sciences, vol. 9, no. 2, pp. 69-77. https://doi.org/10.1027/1614-2241/a000056