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Advances in Fuzzy Systems
Volume 2014, Article ID 896150, 9 pages
Research Article

Fuzzy Approach for Group Sequential Test

Department of Statistics, Hacettepe University, 06800 Ankara, Turkey

Received 10 November 2013; Revised 26 December 2013; Accepted 26 December 2013; Published 19 February 2014

Academic Editor: Ping Feng Pai

Copyright © 2014 Duygu İçen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Buckley’s approach (Buckley (2004), (2005), (2006)) uses sets of confidence intervals by taking into consideration both of the uncertainty and impreciseness of concepts that produce triangular shaped fuzzy numbers for the estimator. This approach produces fuzzy test statistics and fuzzy critical values in hypothesis testing. In addition, the sample size is fixed for this test. When data comes sequentially, however, it is not suitable to study with a fixed sample size test. In such cases, sequential and group sequential tests are recommended. Unlike a sequential test, a group of sequential test provides substantial savings in sample and enables us to make decisions as early as possible. This intends paper to combine the benefits of group sequential test and Buckley's approach using -cuts. It attempts to show that using -cuts can be used within the group sequential tests. To illustrate the test more explicitly a numerical example is also given.