摘要:

AbstractWe have begun to experience in data gathering and analysis in modern ecological and environmental work a space age/stone age syndrome. Also we are challenged to break into the cycle of no information, new information, and non‐information while dealing with soft data, hard looks, and prudent decision‐making involving errors of the third and the fourth kind in addition to those of the first and the second type.Weighted distribution methods arise in the context of data gathering, modeling, inference, and computing, and help provide a unified approach in dealing with encountered d

ISSN:1180-4009    

DOI:10.1002/env.3770020402

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe semivariogram plays a central role in a geostatistical analysis of spatially correlated environmental data. A valid semivariogram model is selected, and the parameters of that model are estimated, before kriging (spatial prediction) of environmental variables is performed. These inference procedures are generally based upon examination of the empirical semivariogram, which consists of average squared differences of data taken at sites lagged the same distance apart in the same direction. In some situations, the investigator may wish to estimate some attributes of the semivariogram more precisely than others. The efficient estimation of such attributes is affected significantly by the spatial configuration of the network of sites where measurements are taken. In this paper, an approach to network design is proposed that emphasizes the utility of the network for estimating selected attributes of the semivariogram. Details are given as to how the approach can be applied to precisely estimate (a) the ratio of nugget effect to sill, (b) a set of compatibility‐determining attributes, and (c) a geometric anisotropy. Acid deposition data taken from a sampling network in the eastern United States are used to further illustrate the approac

ISSN:1180-4009    

DOI:10.1002/env.3770020403

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe respiratory health condition of the workers in mines is affected by concentration of dust mainly deposited due to production activities. Two standard dust sampler instruments (NY and ME) were used to measure the dust concentration in two mining complexes in Labrador, Canada. The dust absorption capacity of these samplers is assumed to be influenced by temperature and humidity of the experimental environment. This paper examines the relative performance of the two dust samplers NY and ME taking the covariates temperature and humidity into account. This is achieved through a robust regression analysis by regressing the ratio of dust concentrations measured by NY and ME on temperature and humidity. Also robust regression results are compared with classical multiple regression based on the power transformation.

ISSN:1180-4009    

DOI:10.1002/env.3770020404

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe classical problem of pooling data of two independent random samples drawn possibly from two identical arbitrary populations is considered. Decision to pool the two samples or not is based on the outcome of the preliminary test and then a shrinkage technique is used. In an asymptotic setup, the distributional risks of the proposed estimators are derived and compared. This study reveals the robustness property of the proposed shrinkage preliminary test maximum likelihood estimator (SPTMLE) when the assumed restraints may not hold. It is shown that the proposed estimator provides a wider range than the usual preliminary test maximum likelihood estimator (PTMLE) in which it dominates the classical estimator. More importantly, the SPTMLE provides more meaningful size for the preliminary test.

ISSN:1180-4009    

DOI:10.1002/env.3770020405

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractVariably of estimates in natural resources and the environmental sciences is high, and methods for increasing precision are important. Three different approaches have been applied to increase precision of sample based estimates by including auxiliary variables: these are stratified sampling, sampling with probability of selection proportion to size, and ratio estimation. The objective of this study was to determine the conditions under which each of these methods had a small error of estimate. Bivariate normal populations were generated with different coefficients of variation for both the variable of interest and the auxiliary variable, and with different correlations between the auxilliary variable, and with different correlations between the auxiliary variable and the variable of interest. All three approaches for increasing precision were applied to estimate the population means and determine the precision of the estimates relative to that of simple random sampling. Stratified sampling was the most precise method unless the coefficients of variation of both the variable of interest and the auxiliary variable were small and the correlation was high. This condition does not occur often in natural resources or the environmental sciences, and stratified sampling most often would be the best method for increasing precision.

ISSN:1180-4009    

DOI:10.1002/env.3770020406

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe likelihood ratio criterion for testing the mutual independence ofqsubvectors of anl‐dimentional normal vector on the basis of a sample of sizeNonlcomponents and of an incomplete sample of sizeMonrcomponents (r

ISSN:1180-4009    

DOI:10.1002/env.3770020407

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

ISSN:1180-4009    

DOI:10.1002/env.3770020401

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY