Time-truncated attribute sampling plans using EWMA for Weibull and Burr type X distributions

Acceptance sampling, widely used in various production industries, is a very vital tool of quality control. In this paper, a new attribute acceptance-sampling plan is developed based on the exponentially weighted moving average statistic under a time-truncated life test when the product lifetime follows the Weibull distribution or the Burr type X distribution. The performance measures such as the probability of acceptance and the average sample number are derived. Tables are constructed for the selection of optimal parameters of the proposed sampling plan so as to minimize the average sample number satisfying the producer's and the consumer's risks. Illustrative example is also given for the application of the proposed plan. It is also shown that the proposed plan requires a smaller sample size compared to the single sampling plan.     

Specific niche requirements drive long-term survival and growth of translocated epiphytic orchids in an urbanised tropical landscape

Urbanisation is expanding at an unprecedented rate, affecting multiple taxa the world over. Ex situ conservation practices in urban areas (e.g. managed relocation) can help mitigate species extinction. However, systematic evaluations of ex situ practices and quantification of niche spaces, especially in urban areas, are largely lacking. Using epiphytic orchids as a study system, we translocated 13 propagated native species (2251 individuals) on 99 host trees across six urban sites. After 5 years, 12 of 13 species showed survival rates above 50% and 9 of 11 species exhibited positive growth. Generalised linear mixed models revealed that species and presence of humus corresponded to orchid survival, whereas the fork microsite and height from ground corresponded to orchid growth. Species-wise, the biophysical factors that were associated with survival and growth varied widely, with 7 of 11 species showing distinct interactions with more than one factor. Notably, the presence of humus and relative humidity influenced the survival of 4 of 11 species. This study suggests that managed relocation can serve as a viable conservation strategy for native orchids and possibly other epiphytes as well. We propose that species-specific niche requirements are identified and integrated into intervention actions.     

A Child Labour Estimator: A Case of Bahawalpur Division

Social Indicators Research - Child labor is a distressing issue. There have been many attempts to estimate its magnitude. It is attempted here to develop an estimator to assess the magnitude of...     

EWMA and DEWMA repetitive control charts under non-normal processes

In this paper, we present a repetitive sampling method to construct control charts using exponentially weighted moving averages (EWMA) and double exponentially weighted moving averages (DEWMA) to monitor shift in the process. For non-normal processes, t-distribution with various degrees of freedom (i.e. df=4,10,20,40,50) is used as symmetric distribution, gamma distribution with unit scale parameter and various shape parameters (i.e. 0.5,1,2,3,4) is used as positively skewed distribution and Weibull distribution with unit scale parameter and various shape parameters (i.e. 10 and 20) is used as negatively skewed distribution. We use Monte Carlo simulations to check whether the process is out of control. We use average run length as a tool to find the ability of proposed control charts to identify a shift earlier in a process, as compared to other control charts currently used to monitor the same type of process. The proposed control charts are applied to two real datasets.KEYWORDS: Control charts, EWMA statistic, DEWMA statistic, t distribution, gamma distribution, Weibull distribution     

Islamic Religious Organizations Across Borders: The Case of the Pakistani Migrant Muslim Community in Korea (South)

With the formation of small migrant communities in foreign lands, some religious organizations migrate along with the migrants and play a part in shaping and reshaping the socio-religious experiences of respective migrants. This paper looks into how Islamic religious organizations have been established in South Korea; how the socio-religious experience of the Pakistani Muslim minority community in Korea is mediated by these organizations; and what is the impact of this mediation on the daily socio-religious lives of the migrants. Two Islamic religious organizations—Dawat-e-Islami and Minhaj-ul-Quran—have been discussed here which originated in Pakistan and have been working around the world including Korea. Using the conceptual framework of social capital, we elaborate on three stages for establishment and working of these religious institutions: deployment of social capital for initiation; reinforcement of social capital for establishment; and sustenance with social capital over a course of time. This paper proposes that these religious organizations are established by the migrant community because of the social capital created within, as opposed to any master plan from the respective parent organizations in the country of origin. Further, these organizations become connected to mainstream organizations as a result of community efforts.     

Does Nominal Devaluation Precede Real Devaluation? The Case of The Philippines

This paper attempts to examine the link between nominal devaluation and real devaluation with special reference to the Philippines. In doing so, we have used log linear relationship between the variables and have employed some sophisticated tests such as Ng–Perron unit root test, autoregressive distributive lag model, and dynamic ordinary least squares test for the long run correlation. The findings of the study with the Philippino quarterly data suggest that not only in the long run, but also in the short run, nominal devaluation leads to real devaluation.

EXPONENTIAL SMOOTHING AND NON‐NEGATIVE DATA

The most common forecasting methods in business are based on exponential smoothing, and the most common time series in business are inherently non‐negative. Therefore it is of interest to consider the properties of the potential stochastic models underlying exponential smoothing when applied to non‐negative data. We explore exponential smoothing state space models for non‐negative data under various assumptions about the innovations, or error, process. We first demonstrate that prediction distributions from some commonly used state space models may have an infinite variance beyond a certain forecasting horizon. For multiplicative error models that do not have this flaw, we show that sample paths will converge almost surely to zero even when the error distribution is non‐Gaussian. We propose a new model with similar properties to exponential smoothing, but which does not have these problems, and we develop some distributional properties for our new model. We then explore the implications of our results for inference, and compare the short‐term forecasting performance of the various models using data on the weekly sales of over 300 items of costume jewelry. The main findings of the research are that the Gaussian approximation is adequate for estimation and one‐step‐ahead forecasting. However, as the forecasting horizon increases, the approximate prediction intervals become increasingly problematic. When the model is to be used for simulation purposes, a suitably specified scheme must be employed.     

The Impact of Organizational Change on Employee Turnover Intention: Does Stress Play a Mediating Role?

This study examined the relationship between change interventions and employee turnover intention to see if change interventions lead to increased employee turnover intention. Moreover, the mediating role of employee stress was tested. Data were collected from 162 respondents working at various administrative positions in a large public organization. The results indicate that employee turnover intention is positively correlated to human process, techno structural, human resources, and strategic interventions. Limitations and direction for future research are provided.     

On designing new optimal synthetic Tukey’s control charts

Tukey’s control chart is generally used for monitoring the processes where the measurement process physically damages the product. It is based on single observation and robust to outliers. In this paper, two optimal synthetic Tukey’s control charts are proposed by integrating the conforming run length chart with the Tukey’s control chart and its modification. The performance comparison of the proposed charts with the existing Tukey’s control charts is made by using out-of-control average run length and extra quadratic loss as performance metrics. The proposed charts offer better protection against the process shifts as compare to the existing Tukey’s control charts when the underlying process distribution is symmetric or asymmetric. Simulation studies also establish the supremacy of the proposed control charts over the existing Tukey’s control charts. In the end, an illustrative example based on a real data set of the combined cycle power plant is provided for practical implementation.