Generation of multivariate distributions by vertical density representation

Troutt (1991,1993) proposed the idea of the vertical density representation (VDR) based on Box-Millar method. Kotz, Fang and Liang (1997) provided a systematic study on the multivariate vertical density representation (MVDR). Suppose that we want to generate a random vector X[d]Rⁿthat has a density function ?(x). The key point of using the MVDR is to generate the uniform distribution on [D]_?(v) = {x :?(x) = v} for any v > 0 which is the surface in RⁿIn this paper we use the conditional distribution method to generate the uniform distribution on a domain or on some surface and based on it we proposed an alternative version of the MVDR(type 2 MVDR), by which one can transfer the problem of generating a random vector X with given density f to one of generating (X, X_n+i) that follows the uniform distribution on a region in Rⁿ⁺¹defined by ?. Several examples indicate that the proposed method is quite practical.     

Multi-product batch production on a single machine—A problem revisited

When several products are processed one at a time on a single machine, the conventional approach of computing the economic batch quantity for each product cannot apply. An example for six products is considered, where the total production capacity on regular time is inadequate, so that overtime has to be used at an extra cost. A simple method is described for solving this problem when each product is produced once during a production cycle, the objective being to minimize the total set-up and holding costs per day. Schedules which involve batch splitting can reduce these costs further, and a guideline is proposed for the construction of sub-cycles. The results compare favourably with lower bounds computed for the purpose.     

Modeling large electorates with Fourier series, with applications to Nash equilibria in proximity and directional models of spatial competition

 In this paper we introduce harmonic analysis (Fourier series) as a tool for characterizing the existence of Nash equilibria in two-dimensional spatial majority rule voting games with large electorates. We apply our methods both to traditional proximity models and to directional models. In the latter voters exhibit preferences over directions rather than over alternatives, per se. A directional equilibrium can be characterized as a Condorcet direction, in analogy to the Condorcet (majority) winner in the usual voting models, i.e., a direction which is preferred by a majority to (or at least is not beaten by) any other direction. We provide a parallel treatment of the total median condition for equilibrium under proximity voting and equilibrium conditions for directional voting that shows that the former result is in terms of a strict equality (a knife-edge result very unlikely to hold) while the latter is in terms of an inequality which is relatively easy to satisfy. For the Matthews [3] directional model and a variant of the Rabinowitz and Macdonald [7] directional model, we present a sufficiency condition for the existence of a Condorcet directional vector in terms of the odd-numbered components of the Fourier series representing the density distribution of the voter points. We interpret our theoretical results by looking at real-world voter distributions and direction fields among voter points derived from U.S. and Norwegian survey data. Received: 7 July 1995 / Accepted: 14 May 1996     

PRODUCT CHARACTERISTICS, HUMAN CAPITAL, AND LABOR MARKET SEGMENTS:

This article contends that one key to understanding different forms of work organization lies in the nature of the products being created. Product characteristics are proposed to be critical determinants of the type of human capital, either general or firm specific. Following from prior theory, labor market barriers develop based on type of human capital. These barriers then have a direct bearing on employee rewards. The nature of the product distinction is captured with a comparison of two product-types (goods and services) conceived as theoretically distinct. General skills are hypothesized to be more important in the service-producing sector, while firm-specific skills are hypothesized to be more important in the goods-producing sector. Empirical analyses using the 1991 General Social Survey compare workers in the service-producing and goods-producing sectors to illustrate differences in the salience of firm-specific and general skills. Two hypotheses are supported. Firm-specific skills have a stronger effect on earnings in manufacturing industries than in service industries. Also, skills acquired from on-the-job training, when compared with other skills, are more weakly related to service employee rewards. These distinctions between sectors suggest insights into structures unique to the service employment workplace.     

Family-Responsive Variables and Retention-Relevant Outcomes Among Employed Parents

This study examined the influence offamily-responsive variables and the moderating influence of gender on the retention-relevant outcomes of organizational commitment and turnover intentions. Data were obtained with the aid of structured questionnaires from employed parents (N = 228) in a human service authority in Hong Kong. Results of regression analysis revealed that satisfaction with work schedule flexibility and supervisor work family support were related to both retention-relevant outcomes. Contrary to our prediction, gender did not moderate the influence of any of the family-responsive variables on the retention-relevant outcomes. Limitations of the study, directions for future research and implications of the findings for enhancing the effectiveness of family-responsive human resource policies are discussed.     

Intrinsic Growth Rates and Net Reproduction Rates in the Presence of Migration

Conventional measures of long‐term population growth such as the intrinsic growth rate and the net reproduction rate assume migration rates to be zero. We develop expressions for analogous measures that register the impact of net migration rates, and we develop a simple method of estimating their values. Applying these new measures to data for developed countries shows that allowance for migration raises net reproduction rates by 0.2‐0.3 in areas of overseas European settlement and by approximately half as much in Northern and Western Europe. The newly defined intrinsic growth rates in Eastern Europe are exceptionally low at ‐1.7 percent to ‐2.4 percent per annum. In contrast, the migration‐adjusted intrinsic growth rate of the United States exceeds those of Asia and Latin America. The formulas and estimation procedures described should allow a more precise understanding of the implications of current migration patterns for long‐term growth prospects.     

The Role of School Contexts in Adolescents' Weight‐loss Behaviors and Self‐perceptions of Overweight

Using the National Longitudinal Study of Adolescent to Adult Health and multilevel modeling, this study investigates the role high school social contexts play in the development of adolescents' weight‐loss behaviors and overweight self‐perceptions. Overall, the results indicate that there is an important association between adolescents' weight‐loss behaviors and self‐perceptions of overweight and the weight‐related context of their school. For example, both adolescent boys and girls are less likely to engage in weight‐loss behaviors when overweight is prevalent among their same‐sex schoolmates. However, gender differences are also found. For example, while adolescent boys' self‐perceptions of overweight are significantly associated with their same‐sex schoolmates' characteristics and behaviors, this is not the case for adolescent girls. Overall, these findings suggest that meso‐level social contexts—such as schools—may be particularly important to how individuals incorporate macro‐level beliefs or values—such as gendered body ideals—into their own behaviors and self‐concepts.