对《高海拔缺氧、文化和人类生育力或生殖能力》一文的评论

在戈尔斯坦、查隆和比尔最近发表的论文--<高海拔缺氧、文化和人类生育力或生殖能力的比较研究>(载<美国人类学家>85:28-49,1983)中,作者试图把文化当作解释喜马拉雅山区居民人口差异问题的惟一因素,完全排除了缺氧的影响,同时他们还对别人过去发表的用缺氧进行解释的相关材料(魏兹以及其他人1978;本格汉和塞奇勒1980;古朴塔1980)提出批评.     

Age-of-Arrival Effects on the Education of Immigrant Children: A Sibling Study

We analysed the effects of late entry on the human capital of immigrant children, and investigated the channels via which age-at-migration affects the native-immigrant education gap. Ordinary-least-squares estimates could have been biased if parents factored the age of children into their migration decision. Using a sample of siblings from the 2000 US Census, we employed a family fixed-effects estimation strategy and found a negative and convex relationship between human capital and age-of-arrival. Teenage entrants’ outcomes were worst affected compared to younger entrants. Language was found to be an important mediating factor via which age-of-arrival influenced education. The critical age for English proficiency was 8–10. Age-of-arrival affected education not only through language but also via heterogeneous origin country conditions. The additional privileges of birth-right citizenship, if any, were disentangled from the benefits of zero age-of-arrival for natives. Citizenship by birth provided few advantages, except for college enrollment. Results were robust to sample selection changes.     

Identifying Factors Influencing Perceived Quality of Life (QoL) of Indian Elderly: Case Study of Kolkata,India

Social Indicators Research - Well-being of the Indian elderly is presently a concern in the urban Indian society due to the gradual decline in the capacity of the family to serve as care-givers for...     

Bayesian analysis of competing risks with partially masked cause of failure

Summary. Bayesian analysis of system failure data from engineering applications under a competing risks framework is considered when the cause of failure may not have been exactly identified but has only been narrowed down to a subset of all potential risks. In statistical literature, such data are termed masked failure data. In addition to masking, failure times could be right censored owing to the removal of prototypes at a prespecified time or could be interval censored in the case of periodically acquired readings. In this setting, a general Bayesian formulation is investigated that includes most commonly used parametric lifetime distributions and that is sufficiently flexible to handle complex forms of censoring. The methodology is illustrated in two engineering applications with a special focus on model comparison issues.     

Robust minimum distance inference based on combined distances

The minimum disparity estimators proposed by Lindsay (1994) for discrete models form an attractive subclass of minimum distance estimators which achieve their robustness without sacrificing first order efficiency at the model. Similarly, disparity test statistics are useful robust alternatives to the likelihood ratio test for testing of hypotheses in parametric models; they are asymptotically equivalent to the likelihood ratio test statistics under the null hypothesis and contiguous alternatives. Despite their asymptotic optimality properties, the small sample performance of many of the minimum disparity estimators and disparity tests can be considerably worse compared to the maximum likelihood estimator and the likelihood ratio test respectively. In this paper we focus on the class of blended weight Hellinger distances, a general subfamily of disparities, and study the effects of combining two different distances within this class to generate the family of “combined” blended weight Hellinger distances, and identify the members of this family which generally perform well. More generally, we investigate the class of "combined and penal-ized" blended weight Hellinger distances; the penalty is based on reweighting the empty cells, following Harris and Basu (1994). It is shown that some members of the combined and penalized family have rather attractive properties     

Concerning several methods for estimating crop acreages using remote sensing data

The objective of this paper is to present a comprehensive survey of the proportion estimation methods so far found in the literature and a newly proposed method based on the concept of statistically equivalent blocks. All methods are restricted to the case of normal mixtures only. Graphical and semigraphical techniques are excluded. Several proportion estimation methods have been described and their properties discussed.     

Bayesian Analysis of Masked Series System Lifetime Data

The problem of analyzing series system lifetime data with masked or partial information on cause of failure is recent, compared to that of the standard competing risks model. A generic Gibbs sampling scheme is developed in this article towards a Bayesian analysis for a general parametric competing risks model with masked cause of failure data. The masking probabilities are not subjected to the symmetry assumption and independent Dirichlet priors are used to marginalize these nuisance parameters. The developed methodology is illustrated for the case where the components of a series system have independent log-Normal life distributions by employing independent Normal-Gamma priors for these component lifetime parameters. The Gibbs sampling scheme developed for the required analysis can also be used to provide a Bayesian analysis of data arising from the conventional competing risks model of independent log-Normals, which interestingly has so far remained by and large neglected in the literature. The developed methodology is deployed to analyze a masked lifetime data of PS/2 computer systems.     

Estimation of Acute Toxicity by Fitting a Dose-Time-Response Surface

In acute toxicity testing, organisms are continuously exposed to progressively increasing concentrations of a chemical and deaths of test organisms are recorded at several selected times. The results of the test are traditionally summarized by a dose-response curve, and the time course of effect is usually ignored for lack of a suitable model. A model which integrates the combined effects of dose and exposure duration on response is derived from the biological mechanisms of aquatic toxicity, and a statistically efficient approach for estimating acute toxicity by fitting the proposed model is developed in this paper. The proposed procedure has been computerized as software and a typical data set is used to illustrate the theory and procedure. The new statistical technique is also tested by a data base of a variety of chemical and fish species.     

How economic development can overcome culture: Demographic change in Punjab,India

This paper looks at the recent declines in fertility and mortality that have occurred in the state of Punjab in India and examines the evidence on the proposition that these have resulted from changes in the sociocultural structure of Punjab - especially those aspects of this structure which influence levels of female status. The article concludes that in fact rates of birth and death (especially at the older ages) have fallen in spite of the persistence of cultural norms and practices that limit female autonomy and that should therefore theoretically favour high fertility and mortality. It is suggested that at this stage of the state's demographic transition it might be more useful to look for causes in the relatively remarkable economic prosperity that the area has witnessed in the last two decades.