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31.
32.
Moving Extremes Ranked Set Sampling (MERSS) is a useful modification of Ranked Set Sampling (RSS). Unlike RSS, MERSS allows
for an increase of set size without introducing too much ranking error. The method is considered parametrically under exponential
distribution. Maximum likelihood estimator (MLE), and a modified MLE are considered and their properties are studied. The
method is studied under both perfect and imperfect ranking (with error in ranking). It appears that these estimators can be
real competitors to the MLE using the usual simple random sampling (SRS). 相似文献
33.
Effect of Sociocultural Context and Parenting Style on Scholastic Achievement among Iranian Adolescents 总被引:1,自引:0,他引:1
Seyed Mohammad Assadi Nayereh Zokaei Hossein Kaviani Mohammad Reza Mohammadi Padideh Ghaeli Mahmood Reza Gohari Fons J. R. van de Vijver 《Social Development》2007,16(1):169-180
School grades, family demographics and responses to the parental authority questionnaire were assessed in 240 eighth‐grade students in the southern, central and northern parts of Tehran, Iran's capital. The result showed that poorer families with traditional values had more authoritarian attitudes toward parenting than richer families with more modern values. In contrast to the studies conducted in East Asian societies, the current study found that authoritative parenting was the style associated with the highest academic outcome. Tests of mediation and moderation effects showed that the relation between parenting style and academic outcome was independent of sociocultural context. 相似文献
34.
35.
Adaptive allocations in stratified sampling design are suitable for studying Biological and Environmental populations. Biologists tend to use the conventional stratified estimator for an adaptive allocation sampling design in spite of its adaptive nature. In this paper, we have introduced an adaptive allocation sampling design for which the conventional stratified estimator has some desired statistical properties. We conduct a simulation study on a real population. The results show that the conventional stratified estimator for the introduced adaptive allocation sampling design is more efficient than other available estimators. 相似文献
36.
The main objective of this paper is to develop an exact Bayesian technique that can be used to assign a multivariate time series realization to one of several autoregressive sources, with unknown coefficients and precision, that might have different orders. The foundation of the proposed technique is to develop the posterior mass function of a classification vector, in an easy form, using the conditional likelihood function. A multivariate time series realization is assigned to the multivariate autoregressive source with the largest posterior probability. A simulation study, with uniform prior mass function, is carried out to demonstrate the performance of the proposed technique and to test its adequacy in handling the multivariate classification problems. The analysis of the numerical results supports the adequacy of the proposed technique in solving the classification problems with multivariate autoregressive sources. 相似文献
37.
This paper demonstrates the use of maxima nomination sampling (MNS) technique in design and evaluation of single AQL, LTPD, and EQL acceptance sampling plans for attributes. We exploit the effect of sample size and acceptance number on the performance of our proposed MNS plans using operating characteristic (OC) curve. Among other results, we show that MNS acceptance sampling plans with smaller sample size and bigger acceptance number perform better than commonly used acceptance sampling plans for attributes based on simple random sampling (SRS) technique. Indeed, MNS acceptance sampling plans result in OC curves which, compared to their SRS counterparts, are much closer to the ideal OC curve. A computer program is designed which can be used to specify the optimum MNS acceptance sampling plan and to show, visually, how the shape of the OC curve changes when parameters of the acceptance sampling plan vary. Theoretical results and numerical evaluations are given. 相似文献
38.
The estimation of the means of the bivariate normal distribution, based on a sample obtained using a modification of the moving
extreme ranked set sampling technique (MERSS) is considered. The modification involves using a concomitant random variable.
Nonparametric-type methods as well as the maximum likelihood estimation are considered. The estimators obtained are compared
to their counterparts based on simple random sampling (SRS). It appears that the suggested estimators are more efficient.
Also, MERSS with concomitant variable is easier to use in practice than the usual ranked set sampling (RSS) with concomitant
variable. The issue of robustness of the procedure is addressed. Real trees data set is used for illustration. 相似文献
39.
This study assesses the fire safety risks associated with compressed natural gas (CNG) vehicle systems, comprising primarily a typical school bus and supporting fuel infrastructure. The study determines the sensitivity of the results to variations in component failure rates and consequences of fire events. The components and subsystems that contribute most to fire safety risk are determined. Finally, the results are compared to fire risks of the present generation of diesel-fueled school buses. Direct computation of the safety risks associated with diesel-powered vehicles is possible because these are mature technologies for which historical performance data are available. Because of limited experience, fatal accident data for CNG bus fleets are minimal. Therefore, this study uses the probabilistic risk assessment (PRA) approach to model and predict fire safety risk of CNG buses. Generic failure data, engineering judgments, and assumptions are used in this study. This study predicts the mean fire fatality risk for typical CNG buses as approximately 0.23 fatalities per 100-million miles for all people involved, including bus passengers. The study estimates mean values of 0.16 fatalities per 100-million miles for bus passengers only. Based on historical data, diesel school bus mean fire fatality risk is 0.091 and 0.0007 per 100-million miles for all people and bus passengers, respectively. One can therefore conclude that CNG buses are more prone to fire fatality risk by 2.5 times that of diesel buses, with the bus passengers being more at risk by over two orders of magnitude. The study estimates a mean fire risk frequency of 2.2 x 10(-5) fatalities/bus per year. The 5% and 95% uncertainty bounds are 9.1 x 10(-6) and 4.0 x 10(-5), respectively. The risk result was found to be affected most by failure rates of pressure relief valves, CNG cylinders, and fuel piping. 相似文献
40.
Mohammad Ahsanullah 《Statistical Papers》1964,22(2):121-127
A sequence {Xn, n≥1} of independent and identically distributed random variables with absolutely continuous (with respect to Lebesque measure) cumulative distribution function F(x) is considered. Xj is a record value of this sequence if Xj>max(X1,…,Xj?1), j>1. Let {XL(n), n≥0} with L(o)=1 be the sequence of such record values and Zn,n?1=XL(n)–XL(n?1). Some properties of Zn,n?1 are studied and characterizations of the exponential distribution are discussed in terms of the expectation and the hazard rate of zn,n?1. 相似文献