A Similarity Measure Based on Species Proportions

ABSTRACT

There are several indices for measuring the similarity of two populations, including the ratio of the number of shared species to the number of distinct species (Jaccard's index) and the conditional probability of observing a shared species (Smith et al., 1996 Smith , W. , Solow , A. R. , Preston , P. E. ( 1996 ). An estimator of species overlap using a modified beta-binomial model. Biometrics 52 : 1472 – 1477 . [CSA] [CROSSREF] [Crossref], [Web of Science ®] , [Google Scholar]). However, these indices only take into account the number of species and species proportions of shared species. In this article, we propose a new similarity index which includes the species proportions of both the shared and non shared species in each population, and also propose a Nonparametric Maximum Likelihood Estimator (NPMLE) for this index. Bootstrap and delta methods are used to evaluate the standard errors of the NPMLE. Based on a loss function, we also compare a class of nonparametric estimators for the proposed index in various situations.     

Inference on Overlap for Two Inverse Gaussian Populations: Equal Means Case

The inverse Gaussian distribution is often suited for modeling positive and/or positively skewed data (see Chhikara and Folks, 1989 Chhikara , R. S. , Folks , J. L. ( 1989 ). The Inverse Gaussian Distribution . New York : Marcel Dekker . [Google Scholar]) and presents an interesting alternative to the Gaussian model in such cases. We note here that overlap coefficients and their variants are widely studied in the literature for Gaussian populations (see Mulekar and Mishra, 1994 Mulekar , M. , Mishra , S. N. ( 1994 ). Overlap coefficients of two normal densities: equal means case . J. Japan. Statist. Soc. 24 : 169 – 180 . [Google Scholar], 2000 Mulekar , M. , Mishra , S. N. ( 2000 ). Confidence interval estimation of overlap: equal means case . Computat. Statist. Data Anal. 34 : 121 – 137 .[Crossref], [Web of Science ®] , [Google Scholar], and references therein for further details). This article studies the properties and addresses point estimation for large samples of commonly used measures of overlap when the populations are described by inverse Gaussian distributions. The bias and mean square error properties of the estimators are studied through a simulation study.     

On the Similarity Structure of Order Statistics

In this article, we address the similarity structure between pairs of order statistics of an identically distributed independent random variables X₁,…, X_n. The overlapping coefficient (Δ) of Weitzman (1970 Weitzman , M. S. ( 1970 ). Measures of overlap of income distributions of white and Negro families in the United States . Technical Paper No. 22 , Washington , D.C. , U.S.A : Department of Commerce, Bureau of Census . [Google Scholar]), is used to assess the degree of similarity or closeness between pairs of order statistics. It appears that the degree of the similarity between any of such pairs is independent of the parent distribution. Using this notion, it is shown that for i < j, the degree of similarity between distributions of the ith and the jth order statistics decreases as i and j sunder. Some possible biometric applicability of the value of Δ are explored. In particular, the use of this measure in estimation of the number of possible strata, subgroups or natural subdivisions in a population are suggested.     

吉尔吉斯斯坦两次革命之共性及其对中国的影响

吉尔吉斯斯坦在2005年3月和2010年4月分别爆发了两次革命。这两次革命都促使了前任政府的下台。两次革命在爆发原因、背后推手及其民族矛盾等方面都有着共性。这两次革命同时也对邻国的中国产生了一定影响。     

Polynomial regression analysis and response surface methodology in leadership research

Congruence has served as an important research framework for many leadership research topics. Perhaps the most frequently used methodological/statistical approach for testing the congruence framework is polynomial regression analysis (PRA) with response surface methodology (RSM). As this approach was introduced to organizational sciences more than two decades ago, we can now identify the main issues with the use of this approach in leadership research. To systematically investigate these issues, we first review how PRA and RSM have been used in various leadership studies. We then review the levels-of-analysis and rater model assumptions prevalent in PRA in terms of multilevel techniques, choice of centering options, and issues of endogeneity. Finally, to better understand the inconsistencies and variabilities that exist in leadership research, we review the use of two main RSM features and summarize additional statistical techniques for assessment in this realm. Overall, we aim to promote the rigorousness of this methodology within the study of congruence in leadership research by enhancing its capability in theory testing and building.     

A fuzzy robust regression approach applied to bedload transport data

Fuzzy least-square regression can be very sensitive to unusual data (e.g., outliers). In this article, we describe how to fit an alternative robust-regression estimator in fuzzy environment, which attempts to identify and ignore unusual data. The proposed approach concerns classical robust regression and estimation methods that are insensitive to outliers. In this regard, based on the least trimmed square estimation method, an estimation procedure is proposed for determining the coefficients of the fuzzy regression model for crisp input-fuzzy output data. The investigated fuzzy regression model is applied to bedload transport data forecasting suspended load by discharge based on a real world data. The accuracy of the proposed method is compared with the well-known fuzzy least-square regression model. The comparison results reveal that the fuzzy robust regression model performs better than the other models in suspended load estimation for the particular dataset. This comparison is done based on a similarity measure between fuzzy sets. The proposed model is general and can be used for modeling natural phenomena whose available observations are reported as imprecise rather than crisp.     

“天人相分”——中华美学命题诠释之五

“天人相分”的哲学命题和思想传统,对中国美学和艺术的发展产生了重要影响,它在审美主体与自然美的关系上承认自然美的客观性,承认主体的美感是由自然事物的美所引起的,它还是中国绘画艺术中“造化与心源”、“形似与神似”这两对美学范畴的哲学基础和理论来源。     

A penalized likelihood approach to image warping

A warping is a function that deforms images by mapping between image domains. The choice of function is formulated statistically as maximum penalized likelihood, where the likelihood measures the similarity between images after warping and the penalty is a measure of distortion of a warping. The paper addresses two issues simultaneously, of how to choose the warping function and how to assess the alignment. A new, Fourier–von Mises image model is identified, with phase differences between Fourier-transformed images having von Mises distributions. Also, new, null set distortion criteria are proposed, with each criterion uniquely minimized by a particular set of polynomial functions. A conjugate gradient algorithm is used to estimate the warping function, which is numerically approximated by a piecewise bilinear function. The method is motivated by, and used to solve, three applied problems: to register a remotely sensed image with a map, to align microscope images obtained by using different optics and to discriminate between species of fish from photographic images.     

Social contexts and personal relationships: The effect of meeting opportunities on similarity for relationships of different strength

This paper examines the effect of social contexts on similarity in personal relationships. We argue that the effect of social contexts is larger for weaker, and smaller for stronger relationships. Using data from The Survey of the Social Networks of the Dutch (collected in 1999/2000, n = 1007), we first describe where people got to know their acquaintances, friends and partner and that similarity in these relationships with regard to age, level of education, sex, and religion, generally varies. We then inquire whether getting to know each other in a certain context affects similarity, and whether this effect is different for relationships of different strength. Our main conclusion, however, is that the effect of social contexts on similarity is remarkably consistent across partnerships, friendships, and acquaintanceships.     

俄汉喻体的民族审美取向

喻体是比喻的基本要素之一.对喻体所作的语义学和语用学研究表明:人类的共同本性、特征和知识决定了人们在使用喻体时具有共同理念和审美取向.俄语和汉语是两种不同的语言,但俄汉喻体在语义类型和遣字用词方面却有着惊人的相同或相似.然而,由于受不同民族的政治、经济、文化、历史、风俗习惯和地理环境等因素的影响,俄汉民族都有着各自不同的审美意识和价值观,从而使喻体蕴涵了典型的民族特征.跨文化分析和研究还进一步表明:俄汉喻体的共性和异性是由不同民族的审美取向的差异决定的.