we develop a two phase sampling procedure to determine the sample size necessary to estimatethe population mean of a normally distributed random variable and show that the resulting estimator has preassigned variance and is unbiased under a regular condition. we present a necessary and sufficient condition under which the final sample mean is an unbiased estimator for the population mean.

Abstract: In this paper, the economic design of MSE control chart is extended to the multivariate case. The important feature of this control chart is that it uses the target value instead of the process mean. According to Taguchi's viewpoint, any deviation from the target value represents a kind of loss. Therefore, we construct the model of economic design by considering not only the control c...

Categorical data appears in various places, and dealing with it has been a major concern in analysis fields. However, representing not only global trends but also local trends of data simultaneously by conventional techniques is difficult. We propose a visualization method called “granular representation” for analyzing categorical data visually. Our approach visually represents data as a set of...

This paper addresses the design of control charts for both variable ( x chart) andattribute (u and c charts) quality characteristics, when there is uncertainty about the processparameters or sample data. Derived control charts are more flexible than the strict crisp case, dueto the ability of encompassing the effects of vagueness in form of the degree of expert’spresumption. We extend the use o...

Development of an efficient process monitoring system has always received great attention. Previous studies revealed that the coefficient variation (CV) is important in ensuring quality, especially for a where its mean and variance are highly correlated. The fact almost all industrial involves minimum two or more related quality characteristics being monitored simultaneously, this paper incorpo...

Modified testing equipment for adjusting the back focal length of a compact camera module (CCM) is proposed. The advantages of this modified testing equipment which includes a conversion lens are that it saves on testing space, offers a smaller sized testing chart, as well as high speed chart changing, and variable object distances. The modified testing equipment can produce a test chart of 38....

While the assumption of normality is required for the validity ofmost of the available control charts for jointmonitoring of unknown location and scale parameters, we propose and study a distribution-free Shewhart-type chart based on the Cucconi statistic, called the Shewhart-Cucconi (SC) chart. We also propose a follow-up diagnostic procedure useful to determine the type of shift the process m...