EOQ model for imperfective items under a one-time-only discount

In practice, when a supplier is confronted with extreme completion in markets, unanticipated surplus in inventory, or change in the production run of a product, he/she may offer a special price discount to motivate buyers to order a special quantity. The purpose of the present paper is to investigate an inventory model for imperfective items under a one-time-only discount, where the defectives can be screened out by a 100% screening process and then can be sold in a single batch by the end of the 100% screening process. The optimal order policies associated with three kinds of effective times of the reduced price are obtained. Finally, a numerical example is provided to illustrate the proposed model.     

Slipping Into and Out of Underemployment: Another Disadvantage for Nonmetropolitan Workers?1

Abstract Underemployment, which goes beyond unemployment to include the working poor, discouraged workers, and involuntary part-time workers, is a useful measure of employment hardship. We argue that underemployment should be included with other conventional indicators of the disadvantaged circumstances of nonmetropolitan (nonmetro) labor, in terms not only of prevalence, but also of the likelihood of transitions into and out of underemployment. We take advantage of the quasi-longitudinal nature of the U.S. Current Population Surveys to estimate models of year-to-year employment transitions for the quarter century 1968 to 1993. We find that (1) adequately employed nonmetro workers are more likely than their more urban counterparts to become underemployed; (2) the nonmetro underemployed are less likely to become adequately employed; (3) statistical controls only strengthen these nonmetro disadvantages; (4) the employment transitions of nonmetro workers are less affected by shifts in the direction of the national economy than are those of metro workers; and (5) nonmetro women are more disadvantaged than women residing elsewhere.     

Public opinion about AIDS policies. The role of misinformation and attitudes toward homosexuals

In an effort to better understand the cognitive and attitudinal factors underlying public opinion on AIDS-related issues, this article proposes and empirically tests a model of the relationships between (1) knowledge of HIV transmission, specifically the misinformation that AIDS can be transmitted easily through casual contact with HIV-infected persons; (2) attitudes toward homosexuals, the most prominent of the social groups presently affected by the AIDS crisis; and (3) support for restrictive public policies aimed at HIV-infected persons. Data from two nationally representative surveys conducted in December of 1985 (N = 2,308) and in July of 1987 (N = 2,095) provide evidence that misinformation about AIDS transmission and negative attitudes toward homosexuals are strong predictors of support for stringent restrictions of persons with AIDS. The findings also suggest that several background factors, in particular, education and political liberalism, may also play decisive roles in influencing levels of support for restricting those infected with the AIDS virus.     

A semiparametric extended hazard regression model with time-dependent covariates

We introduce a general class of semiparametric hazard regression models, called extended hazard (EH) models, that are designed to accommodate various survival schemes with time-dependent covariates. The EH model contains both the Cox model and the accelerated failure time (AFT) model as its subclasses so that we can use this nested structure to perform model selection between the Cox model and the AFT model. A class of estimating equations using counting process and martingale techniques is developed to estimate the regression parameters of the proposed model. The performance of the estimating procedure and the impact of model misspecification are assessed through simulation studies. Two data examples, Stanford heart transplant data and Mediterranean fruit flies, egg-laying data, are used to demonstrate the usefulness of the EH model.     

Measuring relative efficiency of government-sponsored R&D projects: A three-stage approach

Without considering differences in operating environment, traditional methods of efficiency evaluation are suffering from external environmental influences. This study presents an alternative approach for assessing the relative efficiency of government-sponsored research and development projects (GSP). A three-stage approach employing data envelopment analysis to evaluate efficiency and Tobit regression to control external variables was applied to 110 projects over 9 years. This study finds that firm size, industry, and ratio of public subsidy on research and development (R&D) budget of recipient firm significantly influences the technical efficiency of GSP in Taiwan. After controlling these external variables, the mean value of technical efficiency in the third stage increases and becomes significantly different to that in the first stage. Most GSPs increase their returns when their projects are scaled up. Furthermore, government policy makers must establish the upper-limit ratio of subsidies on R&D budgets of recipient firms to avoid inefficient use of public funds.     

The asymptotic distribution of the process capability index Cpmk

The main result of this paper is that under some regularity conditions, the distribution of an estimator of the process capability index C_pmk is asymptotically normal.     

Adaptive sequential procedures for comparing new treatments with a standard

In this paper we propose and study two sequential elimination procedures for selecting all new treatments better than a standard or control treatment. These procedures differ from those previously proposed in that we assume variances are unequal and unknown. Expressions for asymptotic expected sample sizes are given. Confidence intervals associated with the procedures are also discussed.     

Using the Fast Fourier Transform to Compute Multiple Comparisons With the Best and Subset Selection Critical Values

Multiple comparison methods are widely implemented in statistical packages and heavily used. To obtain the critical value of a multiple comparison method for a given confidence level, a double integral equation must be solved. Current computer implementations evaluate one double integral for each candidate critical value using Gaussian quadrature. Consequently, iterative refinement of the critical value can slow the response time enough to hamper interactive data analysis. However, for balanced designs, to obtain the critical value for multiple comparisons with the best, subset selection, and one-sided multiple comparison with a control, if one regards the inner integral as a function of the outer integration variable, then this function can be obtained by discrete convolution using the Fast Fourier Transform (FFT). Exploiting the fact that this function need not be re-evaluated during iterative refinement of the critical value, it is shown that the FFT method obtains critical values at least four times as accurate and two to five times as fast as the Gaussian quadrature method.     

Does the market value corporate response to climate change?

Motivated by the controversial debate on mandatory reductions of greenhouse gases in the U.S., this study explores whether the market values corporate response to tackle carbon dioxide emissions. We measure corporate responses using the measure of media tone based on the positive and negative words in each news article. Our results show that the market reacts favorably to the negative media exposure of corporate response to climate change over the announcement period and the one-year period, which implies that the socially responsible action to tackle climate change is costly. We further find that the positive response is less pronounced for firms from polluting industries and firms with poor environmental performance.