TY - JOUR
T1 - Bootstrap Testing of Central Tendency Nullity Over Paired Fuzzy Samples
AU - Tenekedjiev, Kiril
AU - Nikolova, Natalia
AU - Rodriguez, Rosa M.
AU - Hirota, Kaoru
N1 - Publisher Copyright:
© 2021, Taiwan Fuzzy Systems Association.
PY - 2021/10
Y1 - 2021/10
N2 - 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—Z1 and Z2. We then measure the change ΔZ of Z from Z2 to Z1 and form the fuzzy sample of change Z3. Our aim is to explore if the event has caused statistically significant change ΔZ 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 pvalue 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.
AB - 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—Z1 and Z2. We then measure the change ΔZ of Z from Z2 to Z1 and form the fuzzy sample of change Z3. Our aim is to explore if the event has caused statistically significant change ΔZ 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 pvalue 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.
KW - Degree of membership
KW - Fuzzy empirical cumulative distribution function
KW - Fuzzy sample of change
KW - Simulation modelling
UR - https://www.scopus.com/pages/publications/85111026170
U2 - 10.1007/s40815-021-01074-1
DO - 10.1007/s40815-021-01074-1
M3 - Article
AN - SCOPUS:85111026170
SN - 1562-2479
VL - 23
SP - 1934
EP - 1954
JO - International Journal of Fuzzy Systems
JF - International Journal of Fuzzy Systems
IS - 7
ER -