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41.
Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants. 相似文献
42.
Abstract Despite a high prevalence of poverty among minorities in nonmetropolitan areas, research and policy concerns regarding poverty have continued focusing on metropolitan minorities. This study uses a model integrating individual, household, and structural factors to examine poverty among Latinos, blacks, and Anglos in nonmetropolitan and, for comparative purposes, metropolitan areas, using data from the 1985 Special Texas Census TDHS 1987. The findings show that minorities in nonmetropolitan areas tend to have the highest poverty rates. In addition, consistent as well as divergent patterns exist among the six ethnic-resident groups with respect to the relationships among the various individual, household, and structural factors and poverty. 相似文献
43.
James P. McDermott G. Jogesh Babu John C. Liechty Dennis K. J. Lin 《Statistics and Computing》2007,17(4):311-321
We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In
this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic.
We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve
that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed
for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation.
For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation
study to perform well and to have several distinct advantages over existing methods. 相似文献
44.
Constrained allocation problems with single-peaked preferences: An axiomatic analysis 总被引:1,自引:0,他引:1
Özgür Kıbrıs 《Social Choice and Welfare》2003,20(3):353-362
We introduce a new class of problems that contains two existing classes: allocation problems with single-peaked preferences
and bankruptcy problems. On this class, we analyze the implications of well-known properties such as Pareto optimality, strategy-proofness,
resource-monotonicity, no-envy, equal treatment of equals, and two new properties we introduce, hierarchical no-envy and independence
of nonbinding constraints. Unlike earlier literature, we consider rules that allow free-disposability. We present characterizations
of a rule we introduce on this domain. We relate this rule to well-known rules on the aforementioned subdomains. Based on
this relation, we present a characterization of a well-known bankruptcy rule called the constrained equal awards rule.
Received: 22 June 2000/Accepted: 21 March 2002
This paper is based on the first chapter of my Ph.D. thesis submitted to the University of Rochester. I wish to thank my
advisor, William Thomson, for helpful comments and suggestions. 相似文献
45.
46.
Few researchers have examined organizational variation in the adoption of workplace drug testing, but innovation theory suggests that adoption is more likely when it is compatible with an organization's values, previously introduced ideas, and needs. Using data from the 1997 National Employee Survey, this research models the effects of organizational compatibility, industry, and establishment size on the adoption of drug testing. The data reveal that compatibility, as measured by an organization's rules orientation, presence of an employee assistance program, and mechanization, is associated with the adoption of drug testing. As predicted, the adoption of drug testing varies across industries and by establishment size. 相似文献
47.
Leah K. Vanwey 《Revue europeenne de demographie》2003,19(2):121-145
In this study I consider landownership as a determinant of temporary migrationin a rural area of Thailand. Previous researchon rural areas in developing countries hasfocused on the use of migration to diversifyhousehold incomes across economic sectors andacross geographic areas. I combine thisliterature with economic theories of migrationto understand the effect of land ownership ontemporary migration of household members inNang Rong, Thailand. I estimate regressionmodels predicting the probability of ahousehold having any temporary migrants, andpredicting the number of male or femaletemporary migrants in the household. I findthat households with smaller landholdings arediversifying through migration in order tosupplement rural income, while households withlarger landholdings are diversifying in orderto overcome the absence of accessible credit inthe village. 相似文献
48.
49.
This paper is concerned with joint tests of non-nested models and simultaneous departures from homoskedasticity, serial independence and normality of the disturbance terms. Locally equivalent alternative models are used to construct joint tests since they provide a convenient way to incorporate more than one type of departure from the classical conditions. The joint tests represent a simple asymptotic solution to the “pre-testing” problem in the context of non-nested linear regression models. Our simulation results indicate that the proposed tests have good finite sample properties. 相似文献
50.
Squared residual autocorrelations have been found useful in detecting departures from linearity in time series models. This is especially the case with data exhibiting heterogeneity in variances. A rank test is proposed which is much more robust than its parametric counterpart. 相似文献