Combined double sampling and variable sampling interval np chart

A combined double sampling and variable sampling interval (DSVSI) np chart is investigated in this study. The optimal design of the DSVSI np chart is based on minimizing the out-of-control average time to signal. From the numerical results, the DSVSI np chart performs reasonably well in comparison with the standard np chart, double sampling np chart, synthetic double sampling np chart, and other existing np type control charts for detecting increases in the process of fraction non conforming, based on the zero-state case. An example is provided to illustrate the application of the DSVSI np chart.     

A new non-parametric multivariate EWMA sign control chart for monitoring process dispersion

In this paper, a new non-parametric multivariate exponentially weighted moving average (NMEWMA) sign chart is proposed for monitoring the process dispersion. The run length characteristics of the NMEWMA sign chart are computed with the help of Markov chain and Monte Carlo simulations. Moreover, the NMEWMA sign chart is also used to detect changes in the process mean and dispersion simultaneously. An illustrative example is also used to explain the implementation of proposed control chart.     

The double sampling S2 chart with estimated process variance

This paper proposes useful exact bounds for the parameters of the double sampling S² chart with known process variance and it also investigates the properties of the double sampling S² chart with estimated process variance, in terms of the average run length, the standard deviation of the run length and the average sample size, providing a numerical comparison with the known process variance case. It also provides guidelines to systematically design the double sampling S² chart both with known and estimated process variance and proposes two optimal design procedures with estimated process variance, for (a) minimizing the out-of-control average run length and (b) minimizing the out-of-control average sample size.     

Multivariate Synthetic |S| Control Chart with Variable Sampling Interval

A variable sampling interval (VSI) feature is introduced to the multivariate synthetic generalized sample variance |S| control chart. This multivariate synthetic control chart is a combination of the |S| sub-chart and the conforming run length sub-chart. The VSI feature enhances the performance of the multivariate synthetic control chart. The comparative results show that the VSI multivariate synthetic control chart performs better than other types of multivariate control charts for detecting shifts in the covariance matrix of a multivariate normally distributed process. An example is given to illustrate the operation of the VSI multivariate synthetic chart.     

Adjusting for Change of Status in International Migration: Demographic Implications

The calculation of net immigration for the purpose of estimating the resident population in Australia is based on net permanent and long–term (12 months or more) movements into and out of the country. All international movements with duration of stay in Australia or travel abroad of less than 12 months (defined as short–term) are excluded. However, changes between short–term and long–term/permanent status can occur when people extend or shorten their stay or travel. Because net immigration is a significant component of Australia’s population growth (accounting for 40–50 per cent of annual growth), adjusting for these changes in migration status is thought to result in better estimates of net immigration and the resident population. The paper shows that adjusting for change of status can have a large impact on net immigration, particularly when the immigrant intake is small. Failure to adequately adjust for change of status can also lead to misleading conclusions about the relative contributions of net temporary and permanent movements to total net immigration. The effect on the resident population, however, is relatively small, being less than 1 per cent of the total population. The paper also addresses the question of how important it is for countries to adjust for change of migrant status in international migration statistics in the context of increasing international mobility.     

Sponsorship of Relatives for Migration and Immigrant Settlement Intention

The paper examines how important family reunification is in immigrants' decision to settle permanently in their country of destination. Using longitudinal data for a cohort of recent immigrants to Australia, it examines whether migrants' permanent settlement intention reported soon after arrival is related to their family sponsorship patterns and intention to sponsor, and whether family sponsorship patterns and intention in turn have an effect on immigrants' permanent settlement/return migration decision. The results show that a significant relation exists between sponsorship of close family members for migration and immigrants' permanent settlement intention and that the relation is particularly strong among skilled migrants. The study demonstrates the importance of kinship ties in permanent settlement and return migration decisions and suggests that liberal policies on family reunion migration may minimize settle loss, especially among skilled immigrants.     

Motivation for ISO 14000 certification: development of a predictive model

Environmental issues have become critical concerns of businesses in recent years. The Singapore Environment Ministry is urging organizations to consider adopting the ISO 14000 Environmental Management Standards. The main purpose of this study was to investigate and identify a number of variables which would be able to predict the motivation of organizations in adopting the ISO 14000 Standards. Through extensive literature search eight possible predictive variables/factors (cost savings, top management concern, employee welfare, meeting environmental regulations, meeting customer expectations, concern over trade barriers, following head office environmental practices, and gaining competitive advantages) were identified. In total, 300 pre-tested survey questionnaires were mailed out to companies from the Electronic and Chemical industries in Singapore. A response rate of about 20% was obtained. The survey instrument was tested for reliability and validity. Using stepwise discriminant analysis, a predictive discriminant function was developed. Only four out of the originally identified eight variables were included in the model. Possible benefits of such a model for Singapore and other industrializing countries are highlighted.     

Optimal designs of multivariate synthetic |S| control chart based on median run length

The multivariate synthetic generalized sample variance |S| (synthetic |S|) chart is a combination of the |S| sub-chart and the conforming run length sub-chart. A procedure for optimal designs of the synthetic |S| chart, based on the median run length (MRL), for both zero and steady-state modes are provided by minimizing the out-of-control MRL. The comparative results show that the synthetic |S| chart performs better than the standard |S| chart for detecting shifts in the covariance matrix of a multivariate normally distributed process, in terms of the MRL. An example is given to illustrate the operation of the synthetic |S| chart.     

Stability and change in ethnic identification in Australia: An aggregate level analysis

A cohort approach is used to detect changes in ethnic identification between the 1986 and 2001 Australian censuses. The aim is to observe whether particular ethnic groups were more or less likely to state the same ancestry in 2001 as in 1986. Age-sex specific survival ratios are applied to the ancestry groups in three 15-year age cohorts in 1986 to estimate the number that would have survived to 2001, adjusting for emigration and underenumeration. Some ethnic groups appear to demonstrate remarkable consistency in their ancestry response in the two censuses. Others show an increase in size between the two censuses that could be attributed to differences in the format of the ancestry question and the guidelines and examples provided on the census form. The coding of only two ancestries appears to have contributed to a decrease in the size of some groups.