The FastHCS algorithm for robust PCA

Principal component analysis (PCA) is widely used to analyze high-dimensional data, but it is very sensitive to outliers. Robust PCA methods seek fits that are unaffected by the outliers and can therefore be trusted to reveal them. FastHCS (high-dimensional congruent subsets) is a robust PCA algorithm suitable for high-dimensional applications, including cases where the number of variables exceeds the number of observations. After detailing the FastHCS algorithm, we carry out an extensive simulation study and three real data applications, the results of which show that FastHCS is systematically more robust to outliers than state-of-the-art methods.     

Nonparametric Regression with Sample Design Following a Random Process

Nonparametric regression is considered where the sample point placement is not fixed and equispaced, but generated by a random process with rate n. Conditions are found for the random processes that result in optimal rates of convergence for nonparametric regression when using a block thresholded wavelet estimator. Previous results on nonparametric regression via wavelets on both fixed and random sample point placement are shown to be special cases of the general result given here. The estimator is adaptive over a large range of Hölder function spaces and the convergence rate exhibited is an improvement over term-by-term wavelet estimators. Threshold selection is implemented in a data-adaptive fashion, rather than using a fixed threshold as is usually done in block thresholding. This estimator, BlockSure, is compared against fixed-threshold block estimators and the more traditional term-by-term threshold wavelet estimators on several random design schemes via simulations.     

Immigration,Ethnicity, and Conflict: The California Chinese, 1849–1882*

Drawing on Bonacich's split market theory, the work of Hechter and Blalock on ethnic conflict, and the literature on social movements, the authors develop a model of factors producing conflict between native and immigrant workers. The model identifies the relative size of the immigrant group, the growth of the immigrant population, the desirability of jobs held by immigrant workers, economic conditions, the development of racist ideology among native workers, and the organization of native workers as factors possibly explaining the frequency of incidents of overt ethnic conflict and efforts to institutionalize discrimination through government action. The model is assessed by examining the situation of Chinese immigrants in California between 1849 and 1882. The data suggest that poor economic conditions, a well-developed racist ideology, and well-organized native workers best explain incidents of ethnic conflict and successful efforts to obtain discriminatory government action.     

SYMBOLIC POLITICS IN THE INFORMATION AGE: THE 1996 REPUBLICAN PRESIDENTIAL CAMPAIGNS IN CYBERSPACE

This paper traces the use of the World Wide Web as a medium of political communication during the 1996 American presidential campaigns. Beginning with the Republican campaigns' use of the medium during the primary election season, a typology of uses of the web is outlined. While all campaigns felt it necessary to participate in the World Wide Web, different candidates used the medium differently. Furthermore, no campaign made full use of the much-publicized interactive capacity of the web; they used it more as a new means of transmitting traditional mass-media literature (video, graphics, etc.) and as a way of providing access to large volumes of campaign information (voting records, speeches, position papers, etc.).     

The Effects of Perceived Barriers,Role Models,and Acculturation on the Career Self‐Efficacy and Career Consideration of Hispanic Women

This study used path analysis to examine the relationship between perceived barriers, acculturation, and role model influence on the career self‐efficacy and career considerations of a sample of Hispanic women. Two path models were examined. The male‐dominated model accounted for 15% of the variance, and the female‐dominated model accounted for 26% of the variance. No relationship was found between the variables of interest and male‐dominated career self‐efficacy and consideration. However, perceived barriers were related to female‐dominated career consideration and Anglo acculturation significantly contributed to female‐dominated career self‐efficacy. Results are discussed with regard to career practice and research with Hispanic women.     

Discovering Spatio-Temporal Models of the Spread of West Nile Virus

Emerging infectious diseases are characterized by complex interactions among disease agents, vectors, wildlife, humans, and the environment. Since the appearance of West Nile virus (WNV) in New York City in 1999, it has infected over 8,000 people in the United States, resulting in several hundred deaths in 46 contiguous states. The virus is transmitted by mosquitoes and maintained in various bird reservoir hosts. Its unexpected introduction, high morbidity, and rapid spread have left public health agencies facing severe time constraints in a theory-poor environment, dependent largely on observational data collected by independent survey efforts and much uncertainty. Current knowledge may be expressed as a priori constraints on models learned from data. Accordingly, we applied a Bayesian probabilistic relational approach to generate spatially and temporally linked models from heterogeneous data sources. Using data collected from multiple independent sources in Maryland, we discovered the integrated context in which infected birds are plausible indicators for positive mosquito pools and human cases for 2001 and 2002.