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Bootstrap testing of central tendency nullity over paired fuzzy samples


Tenekedjiev, K and Nikolova, N and Rodriguez, RM and Hirota, K, Bootstrap testing of central tendency nullity over paired fuzzy samples, International Journal of Fuzzy Systems, 23, (7) pp. 1934-1954. ISSN 1562-2479 (2021) [Refereed Article]

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DOI: doi:10.1007/s40815-021-01074-1


Let us have a population of objects that are subjected to a given event. Each object can be assigned a degree of membership to the population. Assume that for a set of objects, a continuous parameter is measured before and after the given event. We can now form two paired fuzzy samples from the population-Z(1) and Z(2). We then measure the change Delta Z of Z from Z(2) to Z(1) and form the fuzzy sample of change Z(3). Our aim is to explore if the event has caused statistically significant change Delta Z of Z for that Population. Therefore, we conduct statistical tests for nullity of the central tendencies (mean, median) of change over paired fuzzy samples. We develop two Bootstrap based simulation algorithms to identify the p(value) of such tests for the mean of change and for the median of change. Each of the algorithms has eight modifications depending on: (a) whether the synthetic fuzzy samples were generated using 'quasi-equal-information generation' (i.e. synthetic fuzzy samples with almost equal amount of information as the original ones) or using 'equal-size generation' (i.e. synthetic fuzzy samples with the same size of fuzzy observations as the original ones); (b) whether the approximated sample cumulative distribution functions (CDF) for the synthetic samples generation are empirical (ECDF), or fuzzy empirical (FECDF); (c) whether we perform a one-tail or two-tail test. We demonstrate the consistency of the developed fuzzy Bootstrap nullity tests on two numerical examples where the central tendencies of change are known. We also present a medical case study, where we compare the proposed techniques with an alternative one that utilizes crisp tests. In that case study, we demonstrate the advantages of fuzzy Bootstrap nullity tests in comparison to standard crisp methods over central tendencies. In our discussions, we outline that to declare significance of change, we focus on a whole cluster of tests over fuzzy paired samples as opposed to relying on individual test results.

Item Details

Item Type:Refereed Article
Keywords:fuzzy sample of change, degree of membership, fuzzy empirical cumulative distribution function, simulation modelling
Research Division:Engineering
Research Group:Control engineering, mechatronics and robotics
Research Field:Automation engineering
Objective Division:Information and Communication Services
Objective Group:Information systems, technologies and services
Objective Field:Computer systems
UTAS Author:Tenekedjiev, K (Professor Kiril Tenekedjiev)
UTAS Author:Nikolova, N (Professor Nataliya Nikolova)
ID Code:152641
Year Published:2021
Deposited By:Information and Communication Technology
Deposited On:2022-08-22
Last Modified:2022-08-22

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