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The aim of this study is to present the fuzzy statistics into group sequential test when response variable has binomial case. Confidence
intervals for fuzzy parameter estimation in group sequential test procedure is applied to construct the related fuzzy test statistic with the
help of Buckley’s approach with r-cuts. Afterwards, this present study
is completed with a numerical application to real data. Finally it is concluded that the fuzzy approach is also applicable for group sequential
tests when response variable has binomial case.