Volume 31, Issue 2

In this article we study a generalization of the Laplace distribution. The generalization is motivated by the recent work of Cordeiro and de Castro [2] and is based on the cumulative distribution function of the Kumaraswamy distribution. We provide a comprehensive description of the structural properties of the subject distribution and its successful application to model some economic data.

This article introduces a new lifetime distribution called the transmuted Erlang-truncated exponential (TETE) distribution. This new distribution generalizes the two parameter Erlang-truncated exponential (ETE) distribution. Closed form expressions for some of its distributional and reliability properties are provided. The method of maximum likelihood estimation was proposed for estimating the parameters of the TETE distribution. The hazard rate function of the TETE distribution can be constant, increasing or decreasing depending on the value of the transmutation parameter Φ⁢[-1,1]${\Phi[-1,1]}$; this property makes it more reasonable for modelling complex lifetime data sets than the ETE distribution that exhibits only a constant hazard rate function. The goodness of fit of the TETE distribution in analyzing real life time data was investigated by comparing its fit with that provided by the ETE distribution and the results show that the TETE distribution is a better candidate for the data. The stability of the TETE distribution parameters was established through a simulation study.

In this paper, we propose acceptance sampling plans for transmuted inverse Rayleigh distribution when the lifetime time is truncated at a predetermined level. We consider various characteristics of the acceptance sampling plans such as confidence levels, acceptance numbers, ratio of the experimental time to such a specified average, minimum requisite sample size to affirm a certain mean lifetime assuming transmuted inverse Rayleigh distribution. The minimum sample size, the operating characteristic function values of the new sampling plans as well as the producer’s risk are obtained and the results are illustrated by examples.

In this work, we investigate a double acceptance sampling plan (DASP) based on truncated life tests when the lifetime of a product follows the half normal distribution. By fixing the consumer’s confidence level, the minimum sample sizes of the first and second samples needful to assert the specified mean life are calculated. The operating characteristic values and the minimum ratios of the mean life to the specified life are also analyzed. Several important tables are provided and a numerical example is given to illustrate the results.