Interannual fluctuations in recruitment and growth of the sardine,Sardinops melanostictus, in the sea of Japan and adjacent waters

Recruitment and growth of the sardineSardinops melanostictus fluctuated markedly in the Sea of Japan and adjacent waters between 1978 and 1993. Stock size was calculated using Virtual Population Analysis and average body length in each age class was determined by the number of annual rings on the scales. There is an inverse correlation between average water temperature at a depth of 50 m in the coastal area of the mainland of Japan in winter (January to March) and recruitmentR defined as the number of individuals at 1 year old. There is also an inverse correlation between spawning stock sizeE and reproductive success in (R/E). A multiple regression model using spawning stock size and water temperature in winter as independent variables can explain 73% of variance in reproductive success. It suggests that both density-dependent and density-independent factors perform important roles determining reproductive success. There is an inverse correlation between body length and stock size and this suggests that there is a density-dependent effect on the growth of the sardine.     

Gender and the Internet

Objective. This article examines whether there are differences in men's and women's use of the Internet and whether any such gender gaps have changed in recent years. Methods. We use data from several surveys during the period 1997–2001 to show trends in Internet usage and to estimate regression models of Internet usage that control for individuals' socioeconomic characteristics. Results. Women were significantly less likely than men to use the Internet at all in the mid–1990s, but this gender gap in being online disappeared by 2000. However, once online, women remain less frequent and less intense users of the Internet. Conclusions. There is little reason for concern about sex inequalities in Internet access and usage now, but gender differences in frequency and intensity of Internet usage remain.     

Principal points for an allometric extension model

A set of \(n\) -principal points of a \(p\) -dimensional distribution is an optimal \(n\) -point-approximation of the distribution in terms of a squared error loss. It is in general difficult to derive an explicit expression of principal points. Hence, we may have to search the whole space \(R^p\) for \(n\) -principal points. Many efforts have been devoted to establish results that specify a linear subspace in which principal points lie. However, the previous studies focused on elliptically symmetric distributions and location mixtures of spherically symmetric distributions, which may not be suitable to many practical situations. In this paper, we deal with a mixture of elliptically symmetric distributions that form an allometric extension model, which has been widely used in the context of principal component analysis. We give conditions under which principal points lie in the linear subspace spanned by the first several principal components.     

A theorem on the covariance matrix of a generalized least squares estimator under an elliptically symmetric error

In a general linear regression model, a generalized least squares estimator (GLSE) is widely employed as an estimator of regression coefficient. The efficiency of the GLSE is usually measured by its covariance (or risk) matrix. In this paper, it is shown that the covariance matrix remains the same as long as the distribution of the error term is elliptically symmetric. This implies that every efficiency result obtained under normal distribution assumption is still valid under elliptical symmetry. An application to a heteroscedastic linear model is also illustrated.     

当前世界危机在《资本论》（1868）和《帝国主义论》（1917）中的阐释

关于本次世界经济危机,马克思主义经济学家认为原因有二：一是认为这场危机是“新自由主义的失败”;二是将其当作由生产过剩引发的资本主义循环性危机去理解。但是,观点二并没有解释这场经济危机为何成为了“百年不遇”的事件;而观点一也没有解释自由主义的失败是资本主义的失败。笔者认为,新自由主义是资本主义衰落的必然结果,所以,新自由主义的失败就是资本主义的失败。为此,对上述两种观点进行了否定,认为这次危机的本质是发达资本主义国家不想适应“零增长”的新的经济社会制度。另外,反对金融资本主义,认为应该重视马克思的生产性劳动理论。     

Gender Inequality in Authority and Autonomy in the Workplace in Japan,Britain, and the United States*

Abstract This study examines gender inequality in the distribution of various aspects of autonomy and authority in the workplace in Japan, Britain, and the United States. In all three societies, there are clear gender gaps in access to autonomy and authority relations, but the distributions are most unequal in Japan. The main part of this study involves the testing of four hypotheses which attempt to explain gender differences in autonomy and authority. The first hypothesis, which focuses on family responsibilities, receives limited support from the Japanese and British data. Japanese and British women are disadvantaged in obtaining managerial positions and supervising other employees by the presence of children. The human capital explanation of gender inequality in the workplace appears to be supported to some extent in Japan and Britain because gender gaps are reduced when we controlled for Render differences in education, tenure and work experience in these countries. The differential access to managerial positions is an important source of gender inequality in workplace social relations in all three countries. Nonetheless, significant gender gaps remain. especially in the United States. When all these factors (family responsibilities, human capital and managerial positions) are taken together, gender gaps are reduced substantially in Japan. In contrast. persistent gender inequality is found in the United States.     

Covariance matrix estimation in a seemingly unrelated regression model under Stein’s loss

Statistical Methods & Applications - A seemingly unrelated regression model has been commonly used for describing a set of different regression models with correlations. This paper discusses...