Design‐Based Inference in a Mixture Model for Ordinal Variables for a Two Stage Stratified Design

In this paper we present methods for inference on data selected by a complex sampling design for a class of statistical models for the analysis of ordinal variables. Specifically, assuming that the sampling scheme is not ignorable, we derive for the class of cub models (Combination of discrete Uniform and shifted Binomial distributions) variance estimates for a complex two stage stratified sample. Both Taylor linearization and repeated replication variance estimators are presented. We also provide design‐based test diagnostics and goodness‐of‐fit measures. We illustrate by means of real data analysis the differences between survey‐weighted and unweighted point estimates and inferences for cub model parameters.     

Assessing non-tariff barriers in Syria

International trade in Syria is highly regulated through a combination of tariffs and non-tariff barriers. At 8% of the value of imports on average, effective tariffs are relatively low. However, non-tariff barriers to trade actually make Syria's trade restrictiveness very high. Comparing world and domestic prices of imports indeed suggests that non-tariff barriers increase the domestic price of imported goods by 17% on average, notably the result of significant quantitative restrictions. Using a computable general equilibrium model, the costs of NTBs on the Syrian economy are assessed. Simulations suggest that reallocation gains resulting from a complete removal of NTBs could be substantial. Accordingly, the key message from the analysis is that trade reform if it focuses only on tariff reduction will have limited growth benefits. On the contrary, if the Government abolishes the widespread non-tariff barriers to trade, including the elimination of quantitative trade restrictions, trade policy can become the central instrument to redress Syria's growth prospects.     

Moments and generating functions for the absortion distribution and its negative binomial analogue

The moments of the absorption are difficult to obtain. The generating functions are basic hypergeometric functions. This paper shows how to define two shift operators that allow elementary arguments to be used to develop recursions for the expected values of general functions. The exact moments of the distribution follow. The generating function for the negative binomial analogue gives the moments directly.     

Extension of the Application of Conway‐Maxwell‐Poisson Models: Analyzing Traffic Crash Data Exhibiting Underdispersion

The objective of this article is to evaluate the performance of the COM‐Poisson GLM for analyzing crash data exhibiting underdispersion (when conditional on the mean). The COM‐Poisson distribution, originally developed in 1962, has recently been reintroduced by statisticians for analyzing count data subjected to either over‐ or underdispersion. Over the last year, the COM‐Poisson GLM has been evaluated in the context of crash data analysis and it has been shown that the model performs as well as the Poisson‐gamma model for crash data exhibiting overdispersion. To accomplish the objective of this study, several COM‐Poisson models were estimated using crash data collected at 162 railway‐highway crossings in South Korea between 1998 and 2002. This data set has been shown to exhibit underdispersion when models linking crash data to various explanatory variables are estimated. The modeling results were compared to those produced from the Poisson and gamma probability models documented in a previous published study. The results of this research show that the COM‐Poisson GLM can handle crash data when the modeling output shows signs of underdispersion. Finally, they also show that the model proposed in this study provides better statistical performance than the gamma probability and the traditional Poisson models, at least for this data set.     

(Q,r)库存中的提前期压缩问题研究

本文在提出了新的具有分段可微特征的提前期压缩成本函数的基础上,构建了一个两阶段(Q,r)库存模型。并在一定服务水平约束条件下,进一步利用成本函数分段可微的特性结合数学分析的理论将原问题分解为一个无约束问题和一个等式约束问题。理论分析及算例表明,可以通过合理的确定模型中的订货量Q、订货点r、提前期加速因子τ等参数值使得在服务水平得到一定提高的同时成本也得到优化。     

Global Trade Models and Economic Policy Analyses: Relevance,Risks and Repercussions for Africa

Computable general equilibrium models are widely used for trade policy analyses and recommendations. There is, however, increasing discomfort with the use of these models, especially in Africa. This article demonstrates that the results of several such studies of the impact of trade reforms in Africa differ drastically in terms of both magnitude and direction, failing to take account of key features of African economies. It also outlines potential consequences of the misuse of CGE models for policy evaluation and suggests pitfalls to be avoided.     

Psychological Implications of Motherhood and Fatherhood in Midlife: Evidence From Sibling Models

Using data from 4,744 full, twin, half‐, adopted, and stepsiblings in the Wisconsin Longitudinal Study, I examine psychological consequences of motherhood and fatherhood in midlife. My analysis includes between‐family models that compare individuals across families and within‐family models comparing siblings from the same family to account for unobserved genetic and environmental endowments that may confound the relationship between parenthood and mental health. Further, I examine whether the psychological effect of parenthood varies among different types of sibling dyads. The findings reveal that parenthood has similar psychological implications for middle‐aged mothers and fathers. Main differences arise from specific configurations of the parental role. The association between parenthood and mental health partly reflects genetic influences but not shared early‐life environment.     

Perceived Equity in the Gendered Division of Household Labor

Despite huge imbalances in the division of housework between women and men, previous studies have found perceptions of equity on the part of women to be much more frequent than feelings of injustice. Taking a comparative perspective on the basis of International Social Survey Program (ISSP) 2002 data (N = 8,556), we find that, on the individual level, the explanatory frameworks that have been found to influence the actual inequality of household division of labor (time availability, resource dependence, and gender ideology) contribute to the explanation of perceptions of equity, in that they interact with the inequality of the household division of labor. On the country level, the gender‐wage ratio and the average level of inequality are important predictors.