New 3-level response surface designs constructed from incomplete block designs

Box and Behnken [1958. Some new three level second-order designs for surface fitting. Statistical Technical Research Group Technical Report No. 26. Princeton University, Princeton, NJ; 1960. Some new three level designs for the study of quantitative variables. Technometrics 2, 455–475.] introduced a class of 3-level second-order designs for fitting the second-order response surface model. These 17 Box–Behnken designs (BB designs) are available for 3–12 and 16 factors. Although BB designs were developed nearly 50 years ago, they and the central-composite designs of Box and Wilson [1951. On the experimental attainment of optimum conditions. J. Royal Statist. Soc., Ser. B 13, 1–45.] are still the most often recommended response surface designs. Of the 17 aforementioned BB designs, 10 were constructed from balanced incomplete block designs (BIBDs) and seven were constructed from partially BIBDs (PBIBDs). In this paper we show that these seven BB designs constructed from PBIBDs can be improved in terms of rotatability as well as average prediction variance, D$D$- and G$G$-efficiency. In addition, we also report new orthogonally blocked solutions for 5, 8, 9, 11 and 13 factors. Note that an 11-factor BB design is available but cannot be orthogonally blocked. All new designs can be found at http://www.math.montana.edu/∼$\sim$jobo/bbd/.     

Characterizations of some continuous distributions

This paper gives characterizations of normal and gamma distributions .via conditional structure.     

Women in waste collection and recycling in Hochiminh City

The generation and management of urban solid waste is an urgent and growing problem in Hochiminh City, as elsewhere in the world. An important contribution to solving the city's waste management problem is made by the recycling industry. The well-organized private system of collection, trade and recycling includes door-to-door itinerant buyers, entirely women, who buy solid waste products from households; a range of small, medium, and big shopkeepers who purchase waste from the buyers; middle-men who link the shopkeepers with the recyclers; and the recycling or production units that transform products for sale to consumers. Earnings of itinerant buyers are low and may be declining. However, their self-employment is critical because they are often the main economic support of their families. Shopkeepers enjoy better standards of living but economic competition and recent environmental regulations threaten the survival of the industry. Policy options are offered for attempting to ensure the survival of recyclers and itinerant buyers, those     

Characterization theorems for some discrete distributions based on conditional structure

The joint distribution of (X,Y) is determined if the conditional expectation E {g(X)|Y = y} is given and the conditional distribution of Y|(X = x) is a conditional power series distribution, where g(·) is a function satisfying some minor conditions.     

The making and transnationalization of an ethnic niche: Vietnamese manicurists

The article addresses how Vietnamese immigrant women developed an urban employment niche in the beauty industry, in manicuring. They are shown to have done so by creating a market for professional nail care, through the transformation of nailwork into what might be called McNails, entailing inexpensive, walk-in, impersonal service, in stand-alone salons, nationwide, and by making manicures and pedicures de riguer across class and racial strata. Vietnamese are shown to have simultaneously gained access to institutional means to surmount professional manicure credentializing barriers, and to have developed formal and informal ethnic networks that fueled their growing monopolization of jobs in the sector, to the exclusion of non-Vietnamese. The article also elucidates conditions contributing to the Vietnamese build-up and transformation of the niche, to the nation-wide formation of the niche and, most recently, to the transnationalization of the niche. It also extrapolates from the Vietnamese manicure experience propositions concerning the development, expansion, maintenance, and transnationalization of immigrant-formed labor market niches.     

A System of Sustainability Indicators for the Province of Thai Binh,Vietnam

Sustainable Development is a broad and universal concept. Indicators are a basis to measure sustainability and to direct policies that aim to achieve a better quality of life. Thai Binh, a coastal province in North Vietnam is strongly concerned about strategic sustainability development. To select a system of sustainability indicators, the Delphi method was applied in 2012. A two-round questionnaire was organized to use with 32 experts, who acted as participants. 69 indicators were selected from 98 listed indicators: 15 related to economic development, 5 to the sea and coastal zone, 1 to the global economic partnership, 4 to consumption and production patterns, 7 to poverty, 3 to governance, 9 to health, 4 to education, 3 to demographics, 2 to natural hazards, 5 to atmosphere, 7 to land, and 3 to freshwater. Conversely, 29 other indicators were rejected. The Delphi method allows indicator selection for identification of the process of sustainability. The system of indicators, as the first important step of the sustainable development process, provides useful information for decision makers and planners as well sustainability strategy. It is planned that the indicators selected should be applied in the province.     

The Prediction Sum of Squares as a General Measure for Regression Diagnostics

Statistics that usually accompany the regression model do not provide insight into the quality of the data or the potential influence of the individual observations on the estimates. In this study, the Q² statistic is used as a criterion for detecting influential observations or outliers. The statistic is derived from the jackknifed residuals, the squared sum of which is generally known as the prediction sum of squares or PRESS. This article compares R ² with Q² and suggests that the latter be used as part of the data-quality check. It is shown, for two separate data sets obtained from regional cost of living and U.S. food industry studies, that in the presence of outliers the Q² statistic can be negative, because it is sensitive to the choice of regressors and the inclusion of influential observations. Once the outliers are dropped from the sample, the discrepancy between Q² and R ² values is negligible.     

Impact of internal migration on the economic well-being of local workers and school dropouts among children in Vietnam

This study examines the impact of migration on local workers and high school dropouts of local students. A conventional approach without addressing the endogeneity issue may lead to biased results. Our endogeneity-corrected estimates show a positive impact of migration on the monthly wages of local workers. A higher share of migrants increases the probability of local workers with employment contracts, social insurance, and holiday pay. Heterogeneity analysis shows that local workers, no matter their educational level, work experience, or occupation sectors, benefit from the inflow of migrants. Finally, migration inflow lowers the probability of high school dropouts among local students. Our findings resulting from rigorous statistical approaches suggest that internal migration produces positive impacts on the economic well-being of local residents, refuting the argument about the adverse effects associated with internal migration.     

Maximizing k-submodular functions under budget constraint: applications and streaming algorithms

Journal of Combinatorial Optimization - Motivated by the practical applications in solving plenty of important combinatorial optimization problems, this paper investigates the Budgeted k-Submodular...     

The role of visa class in the location choices of immigrants in Australia at the regional and neighbourhood scales

Australia’s pro-immigration policies have played a vital role in national population growth, serving to address what would otherwise be chronic labour shortages and population ageing. While migrants to Australian have shown a clear preference for cities and tend to locate with co-ethnics, variations by visa class—employment, family reunification, and asylum—have yet to be fully explored. This paper aims to identify variations in settlement patterns of immigrants in Australia by visa types and the factors underpinning these choices, paying particular attention to ethnic networks and employment opportunities. We apply a series of negative binomial regressions to aggregate census data linked to visa status. At the suburb level, our results show the importance of the presence of compatriots in shaping the location choices of family migrants, with the exception of skilled and humanitarian immigrants from China, Malaysia and Thailand. At the regional level, skilled migrants, including skilled regional migrants, respond to employment opportunities to a greater extent than family and humanitarian migrants.