Abstract:Modified ratio-type estimators of the population mean were suggested using the first or third quartiles of the auxiliary variable based on Simple Random Sampling (SRS) and Extreme Ranked Set Sampling (ERSS) methods. It was found that, the ERSS was more efficient than the SRS based on the same sample size. Also, the ERSS involving the first quartile was superior to the third quartile.
Acceptance sampling plans are statistical procedures that are used for quality control and improvement in cases where it is not possible to test every item in a lot of materials. The outcome of this test determines whether the entire lot is accepted or rejected based on a random sample. In this procedure, an important characteristic of the materials is their lifetime sampling distribution, and this can vary from sample to sample. In this article, a new lifetime distribution, known as an Ishita distribution, is considered for developing a new single-acceptance sampling plan. The new acceptance sampling plan is developed under a condition wherein the mean lifetime test is truncated within a pre-specified time period. Based on this condition, the parameters of the acceptance sampling plan including the operating characteristics function and the minimum sample size are obtained. The producer's risk in relation to the entire lot of materials is derived and illustrated by numerical examples.
Abstract:In this paper, percentile double ranked set sampling (PDRSS) method is suggested for estimating the population mean. The PDRSS method is compared with the simple random sampling (SRS), ranked set sampling (RSS), median ranked set sampling (MRSS) and the extreme ranked set sampling (ERSS) methods. When the underlying distribution is symmetric, it turns out that PDRSS produce unbiased estimators of the population mean and it is more efficient than SRS, RSS, MRSS and ERSS based on the same sample size. For asymmetric distribution considered in this study, it is shown that PDRSS has a small bias and it is more efficient than RSS, MRSS and ERSS for most cases considered in this study.
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