Inflated modified power series distributions with applications

In certain applications involving discrete data, it is sometimes found that X = 0 is observed with a frequency significantly higher than predicted by the assumed model. Zero inflated Poisson, binomial and negative binomial models have been employed in some clinical trials and in some regression analysis problems.

In this paper, we study the zero inflated modified power series distributions (IMPSD) which include among others the generalized Poisson and the generalized negative binomial distributions and hence the Poisson, binomial and negative binomial distributions. The structural properties along with the distribution of the sum of independent IMPSD variables are studied. The maximum likelihood estimation of the parameters of the model is examined and the variance-covariance matrix of the estimators is obtained. Finally, examples are presented for the generalized Poisson distribution to illustrate the results.     

Parameter estimation of nonlinear mixed-effects models using first-order conditional linearization and the EM algorithm

Nonlinear mixed-effects (NLME) models are flexible enough to handle repeated-measures data from various disciplines. In this article, we propose both maximum-likelihood and restricted maximum-likelihood estimations of NLME models using first-order conditional expansion (FOCE) and the expectation–maximization (EM) algorithm. The FOCE-EM algorithm implemented in the ForStat procedure SNLME is compared with the Lindstrom and Bates (LB) algorithm implemented in both the SAS macro NLINMIX and the S-Plus/R function nlme in terms of computational efficiency and statistical properties. Two realworld data sets an orange tree data set and a Chinese fir (Cunninghamia lanceolata) data set, and a simulated data set were used for evaluation. FOCE-EM converged for all mixed models derived from the base model in the two realworld cases, while LB did not, especially for the models in which random effects are simultaneously considered in several parameters to account for between-subject variation. However, both algorithms had identical estimated parameters and fit statistics for the converged models. We therefore recommend using FOCE-EM in NLME models, particularly when convergence is a concern in model selection.     

Are college students health literate?

Abstract

Objective: To examine the health literacy of college students. Participants: A convenience sample of 245 graduate and undergraduate college students. Methods: During February–April of 2018 participants completed the Short Test of Functional Health Literacy which assessed literacy on two passages describing a thyroid scan, and basic healthcare insurance information. Results: Most college students displayed adequate health literacy (99.2%). The ANOVA analyses revealed college classification was the most significant predictor, followed by ethnicity, sex, and primary language. Age was significantly related to health literacy, when holding college classification constant. Interestingly, college major, healthcare work experience, or having health care credentials were not predictors of health literacy. Conclusion: This group of college students had adequate health literacy skills. However, the results of this study revealed demographic disparities that suggest further study.     

Acquisition of Telecommunications Bandwidth Under Economies of Scale in Size and Duration of Contracts*

Significant advances in information technology have brought about increased demand for bandwidth. Buyers of bandwidth often encounter bandwidth prices that are decreasing over time. Additionally, bandwidth prices at any point in time are decreasing in total bandwidth purchased and length of contracts. Therefore, buyers face complex decisions in terms of the number of contracts to buy, their bandwidth, and their lengths. In this article, we formulate models for the acquisition of bandwidth from a buyer's perspective. We begin with a model that allows varying contract durations under deterministic demand and without allowing shortages or overlapping contracts. We then formulate a simpler model, which restricts contract lengths over the planning horizon to be equal. We also solve the problem under probabilistic demand and allowing for shortages, which are satisfied by buying additional bandwidth at a premium. We perform numerical sensitivity analysis to compare the results of the models and illustrate the results with numerical examples. The numerical analyses illustrate that using relatively simple equal‐length contracts produces approximately the same results as the more complicated unequal‐length contract strategy.     

Causal Linkages in Supply Chain Management: An Exploratory Study of North American Manufacturing Firms

In this paper we investigate the key causal linkages in supply chain management. We propose a conceptual framework and test this framework on data from 215 North American manufacturing firms using structural equation modeling techniques. Three major research issues are addressed in this study: Do sourcing decisions affect the degree to which firms achieve manufacturing goals of cost, flexibility, dependability, and quality? Does the degree of manufacturing goal achievement lead to higher customer responsiveness? Does the degree of manufacturing goal achievement lead to higher internal manufacturing performance? The study examines the relationship among sourcing decisions, manufacturing goals, customer responsiveness, and manufacturing performance. The results support the notion that an integrated supply chain involves aligning sourcing decisions to achieve manufacturing goals that are set to respond favorably to the needs of customers.     

World Income Distribution and Tax Reform: What Tax Systems Do Low‐Income Countries Need?

This article develops a new method for assessing relative direct tax burdens across all countries, treating the world as a single economic entity and assuming identical preferences across countries. Empirical results show that the new direct tax burden indices are significantly high in low‐income countries in comparison with middle‐ and high‐income countries. This article argues in favour of narrowing the base of income and capital gains tax in low‐income countries and a long‐term convergence of the tax burden levels across countries. Future research into tax reforms in low‐income countries should focus simultaneously on economic growth, quality of life and the natural environment.     

Bayesian age-stratified joinpoint regression model: an application to lung and brain cancer mortality

Joinpoint regression model identifies significant changes in the trends of the incidence, mortality, and survival of a specific disease in a given population. The purpose of the present study is to develop an age-stratified Bayesian joinpoint regression model to describe mortality trend assuming that the observed counts are probabilistically characterized by the Poisson distribution. The proposed model is based on Bayesian model selection criteria with the smallest number of joinpoints that are sufficient to explain the Annual Percentage Change. The prior probability distributions are chosen in such a way that they are automatically derived from the model index contained in the model space. The proposed model and methodology estimates the age-adjusted mortality rates in different epidemiological studies to compare the trends by accounting the confounding effects of age. In developing the subject methods, we use the cancer mortality counts of adult lung and bronchus cancer, and brain and other Central Nervous System cancer patients obtained from the Surveillance Epidemiology and End Results data base of the National Cancer Institute.     

Competitive Capabilities among Manufacturing Plants in Developing,Emerging, and Industrialized Countries: A Comparative Analysis

Competitive capabilities have been defined as a plant's actual performance relative to its competitors, with the most commonly investigated capabilities being quality, delivery, flexibility, and cost. However, most research in this realm has investigated capabilities within developed countries, and neglected the context of developing and emerging nations, which are increasingly becoming viable economic entities in global supply chains in their own right. The present study fills this gap and carries out a comparative analysis of competitive capabilities among plants in developing, emerging, and industrialized countries. Basing our arguments on the resource‐based view of the firm, we suggest that the influence of competitive capabilities on each other varies among plants in differentially industrialized regions. Specifically, we suggest that, on average, competitive capabilities tend to influence each other to a greater degree in plants in emerging and developing countries compared to industrialized countries. Along similar lines, we suggest that the influence of the four competitive capabilities on performance improvement is manifested more strongly among plants in emerging and developing countries than among plants in industrialized nations. We investigate these contentions with data from 1,211 plants in 21 countries. The results are particularly important for decision makers as they decide on the increasingly global location of their manufacturing operations or the configuration of their global supply chains.     

Regional-sub-cultural explanations of black fertility in the United States

Summary This paper re-examines the relevance of the hypothesis concerning the Southern sub-culture and black fertility in the United States. According to zero-order correlation analysis, Southern-born blacks show higher fertility than those born in other regions. But a dummy-variable regression technique applied to the data from the 1970 public-use sample indicates that the Southern origin - independent of other factors-is not different from other regions. Southern birth has the effect of increasing black fertility, but much less so than birth in the North Central region. Southern blacks show higher fertility because of their lower socio-economic background. It is concluded that geographical regions in the United States have little or no cultural meaning in explaining reproductive behaviour.     

Public opinion and the dimensions of the welfare state

Empirical studies over the last ten years indicate that the public in general still supports the welfare state but not necessarily its beneficiaries nor the allocations required to sustain its activities. Since most of these studies focused only on selected aspects of the welfare state their data do not provide a widespread and comprehensive overview of public opinion regarding the welfare state and its internal dynamics. This article focuses on public opinion with regard to the major components of the welfare state. The sample is drawn from a large urban population in Israel. For each component of the welfare state, three dimensions are studied: governmental allocation, quality of service and number of beneficiaries. The results indicate that public opinion with regard to the various elements of the welfare state is differential and distinct.