电磁波斜入射到分层有耗媒质上的反射和传输系数

为了解决结构型吸收材料的分析和设计中所遇到的反射系数和传输系数的计算问题,提出一种有效的计算方法。此方法简单易行,为结构材料的计算机辅助分析和设计提供了基础。     

Analysis of discrete lifetime data under middle-censoring and in the presence of covariates

‘Middle censoring’ is a very general censoring scheme where the actual value of an observation in the data becomes unobservable if it falls inside a random interval (L, R) and includes both left and right censoring. In this paper, we consider discrete lifetime data that follow a geometric distribution that is subject to middle censoring. Two major innovations in this paper, compared to the earlier work of Davarzani and Parsian [3 N. Davarzani and A. Parsian, Statistical inference for discrete middle-censored data, J. Statist. Plan. Inference 141 (2011), pp. 1455–1462. doi: 10.1016/j.jspi.2010.10.012[Crossref], [Web of Science ®] , [Google Scholar]], include (i) an extension and generalization to the case where covariates are present along with the data and (ii) an alternate approach and proofs which exploit the simple relationship between the geometric and the exponential distributions, so that the theory is more in line with the work of Iyer et al. [6 S.K. Iyer, S.R. Jammalamadaka, and D. Kundu, Analysis of middle censored data with exponential lifetime distributions, J. Statist. Plan. Inference 138 (2008), pp. 3550–3560. doi: 10.1016/j.jspi.2007.03.062[Crossref], [Web of Science ®] , [Google Scholar]]. It is also demonstrated that this kind of discretization of life times gives results that are close to the original data involving exponential life times. Maximum likelihood estimation of the parameters is studied for this middle-censoring scheme with covariates and their large sample distributions discussed. Simulation results indicate how well the proposed estimation methods work and an illustrative example using time-to-pregnancy data from Baird and Wilcox [1 D.D. Baird and A.J. Wilcox, Cigarette smoking associated with delayed conception, J, Am. Med. Assoc. 253 (1985), pp. 2979–2983. doi: 10.1001/jama.1985.03350440057031[Crossref], [Web of Science ®] , [Google Scholar]] is included.     

Anticipated Regret,Risk Perception,or Both: Which is Most Likely Responsible for Our Intention to Gamble?

The current study investigated whether risk aversion or regret aversion could be related to a lower intention to gamble, and whether the type of gambling was a moderator of this relationship. The study took place in Macau, often called “the Las Vegas of East Asia.” A total of 373 Macau residents completed a questionnaire survey dealing with thirteen types of gambling. The results showed that risk perception and anticipated regret had a significant negative effect on the intention to gamble. This negative effect was domain-specific, varying with the type of gambling. Our findings indicated that neither risk aversion nor regret aversion can uniquely explain an individual’s risk-taking tendency consistently. Instead, which factor plays a greater role in lowering the intention to gamble—regret aversion, risk aversion, or both—is itself dependent on the type of gambling involved. The finding that not all gambles are created equal could be useful in gambling prevention and advertising appeal by providing a basis for understanding the role that cognitive and emotional factors play in different types of gambling.     

Enacting everyday feminist collaborations: Reflexive becoming,proactive improvisation and co‐learning partnerships

We trace back our own multi‐year teaching and writing collaboration in academia to theorize feminist collaboration. Drawing from feminist theories and our autoethnographic reflections, we surface three metaphorical processes that constitute feminist collaboration. We consider feminist collaboration as: (i) reflexive becoming, that is, feminist collaborators constantly make sense of what counts as feminist as the group and context evolve; (ii) proactive improvisation, that is, feminist collaborators collectively strive for everyday transformations within situated constraints; and (iii) co‐learning partnerships, that is, feminist collaborators relate to one another in ways that uphold commitments to reflexivity, equity and care. Enacting these processes are fraught with tensions that intertwine with one another to constrain and enable feminist collaboration. We conclude the article by calling for continued theorization and engagement with feminist collaboration.     

Decent Living Standards: Material Prerequisites for Human Wellbeing

Children whose parents experience adverse social, economic, or health-related living conditions are more likely to face similar types of disadvantage in their adult life. However, a limitation of many earlier studies is that they do not account for the multidimensionality of the concept of living conditions, and that the child generation’s life courses are targeted as static and independent from the societal context in which they are imbedded. The current investigation addressed these aspects by focusing on the complexity, duration, and timing of disadvantage with regard to how adverse circumstances in the family of origin are associated with trajectories of social, economic, and health-related living conditions across adulthood. We also examined the role of educational attainment for these associations. Analyses were based a Swedish cohort born in 1953 (n = 14,294). We first conducted sequence analysis, followed by hierarchical cluster analysis, to generate ‘outcome profiles’, i.e. trajectories of adult disadvantage. Second, several indicators of adverse circumstances in childhood were analysed by means of multinominal regression analysis, showing the odds of ending up in the different trajectories. The results indicated that individuals who grew up under adverse conditions were more likely to experience disadvantaged social, economic, and health-related trajectories. This was particularly the case for trajectories characterised by a high degree of complexity, i.e. coexisting disadvantages, and—among men only—by a longer duration of disadvantage. Educational attainment was identified as a powerful mediator, suggesting that efforts to increase equal educational opportunity may be a way of reducing the intergenerational transmission of disadvantage.     

Empirical likelihood confidence intervals under imputation for missing survey data from stratified simple random sampling

Missing observations due to non‐response are commonly encountered in data collected from sample surveys. The focus of this article is on item non‐response which is often handled by filling in (or imputing) missing values using the observed responses (donors). Random imputation (single or fractional) is used within homogeneous imputation classes that are formed on the basis of categorical auxiliary variables observed on all the sampled units. A uniform response rate within classes is assumed, but that rate is allowed to vary across classes. We construct confidence intervals (CIs) for a population parameter that is defined as the solution to a smooth estimating equation with data collected using stratified simple random sampling. The imputation classes are assumed to be formed across strata. Fractional imputation with a fixed number of random draws is used to obtain an imputed estimating function. An empirical likelihood inference method under the fractional imputation is proposed and its asymptotic properties are derived. Two asymptotically correct bootstrap methods are developed for constructing the desired CIs. In a simulation study, the proposed bootstrap methods are shown to outperform traditional bootstrap methods and some non‐bootstrap competitors under various simulation settings. The Canadian Journal of Statistics 47: 281–301; 2019 © 2019 Statistical Society of Canada     

On two-stage shrinkage testtimation

The general procedure of two stage shrinkage testimation formulated in Adlce and Gokhale [Commun. Statist.- Theory Meth. 18, 633-627 (1989)] k further generalized and extended to the multiparameter case. Local optimal-ity result of that paper, in the restricted set up of univariate location families and scalar families, is generalized without any restriction on the parametric family. The local unbiasedness result of that paper is also generalized and in addition local risk- unbiasedness is considered. The optimality and risk-unbiasedness results are proved for the usual matrix loss and their validity for an arbitrary quadratic loss deduced as corollaries.     

Linear approximate ML estimation in scaled Type I generalized logistic distribution based on Type-II censored samples

The scaled (two-parameter) Type I generalized logistic distribution (GLD) is considered with the known shape parameter. The ML method does not yield an explicit estimator for the scale parameter even in complete samples. In this article, we therefore construct a new linear estimator for scale parameter, based on complete and doubly Type-II censored samples, by making linear approximations to the intractable terms of the likelihood equation using least-squares (LS) method, a new approach of linearization. We call this as linear approximate maximum likelihood estimator (LAMLE). We also construct LAMLE based on Taylor series method of linear approximation and found that this estimator is slightly biased than that based on the LS method. A Monte Carlo simulation is used to investigate the performance of LAMLE and found that it is almost as efficient as MLE, though biased than MLE. We also compare unbiased LAMLE with BLUE based on the exact variances of the estimators and interestingly this new unbiased LAMLE is found just as efficient as the BLUE in both complete and Type-II censored samples. Since MLE is known as asymptotically unbiased, in large samples we compare unbiased LAMLE with MLE and found that this estimator is almost as efficient as MLE. We have also discussed interval estimation of the scale parameter from complete and Type-II censored samples. Finally, we present some numerical examples to illustrate the construction of the new estimators developed here.     

Analysis of middle-censored data with exponential lifetime distributions

Recently Jammalamadaka and Mangalam [2003. Non-parametric estimation for middle censored data. J. Nonparametric Statist. 15, 253–265] introduced a general censoring scheme called the “middle-censoring” scheme in non-parametric set up. In this paper we consider this middle-censoring scheme when the lifetime distribution of the items is exponentially distributed and the censoring mechanism is independent and non-informative. In this set up, we derive the maximum likelihood estimator and study its consistency and asymptotic normality properties. We also derive the Bayes estimate of the exponential parameter under a gamma prior. Since a theoretical construction of the credible interval becomes quite difficult, we propose and implement Gibbs sampling technique to construct the credible intervals. Monte Carlo simulations are performed to evaluate the small sample behavior of the techniques proposed. A real data set is analyzed to illustrate the practical application of the proposed methods.     

Partial Correlation in Terms of Path Coefficients

The distribution of members of the American Statistical Association (ASA) by several demographic and professional measures is characterized. The analysis is based on a 1979 survey of ASA members who resided in the U.S. More detailed analysis focuses on how demographic and professional characteristics affect the distribution of income and the odds of participating in ASA activities. Several interesting observations are made. Years of experience since highest degree is the most important predictor of income. Highest degree and whether employed in academia are also important. There is a significant difference between the distribution of income for men and women; although the difference is insignificant at one year of experience, it increases with the experience level. Although the survey represented a 100% sample of blacks, Hispanics, and native Americans in the ASA, there is insufficient data to formulate a detailed model of income for this minority group; its average income, however, falls below the expected income of the majority population for higher experience levels. For both the odds of attending annual meetings and serving ASA as an officer or committee member, the most important discriminator is the highest degree of the member. Race is also a significant factor: blacks, Hispanics, and native Americans were least likely to attend annual meetings, and Asians and Pacific Islanders were least likely to hold office. Years of experience is important also for predicting the odds of having held office but not of having attended meetings.