“…For these reasons, some authors have considered approaches of fuzzy statistics to deal appropriately with fuzziness in data and hypotheses formulation. In the literature of fuzzy hypothesis testing, there are a few publications considering the sign test in fuzzy environments (see Chukhrova and Johannssen, 3 for a systematic review): - Fuzzy/interval‐valued data caused by the imprecision of observations (see Grzegorzewski, 4,5 Grzegorzewski and Spiewak, 6‐8 Hesamian and Chachi, 9 Hesamian and Taheri, 10 Kahraman et al, 11 Momeni and Sadeghpour‐Gildeh, 12 and Shams and Hesamian 13 ), that is, fuzzy data as perception of a crisp but unobservable random variable (so called epistemic perspective, see Couso and Dubois 14 ), or fuzzy set‐/interval‐valued random variables (so called ontic perspective) (see Grzegorzewski and Spiewak 6,7 ).
- Fuzzy/interval‐valued hypotheses caused by fuzzy quantiles like the fuzzy median (see Grzegorzewski and Spiewak 6,7 ) or imprecision of linguistic statements on quantiles (see Hesamian and Chachi, 9 Hesamian and Taheri, 10 Momeni and Sadeghpour‐Gildeh, 12 and Shams and Hesamian 13 ).
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