Older women who experience mistreatment:circumstances and outcomes

Data from Virginia Adult Protective Services (APS) case files of 95 abused women aged 60 years and older were assessed to establish demographic trends; ability to care for self; type, pattern, and place of abuse; information on witnesses and alleged offenders; and case resolution and outcomes. The most common types of mistreatment reported were neglect, exploitation, and physical abuse. The women typically had several functional limitations and were dependent upon their family members for care. Most cases were not prosecuted, and the majority of women remain at risk for further abuse. Implications of these data for future research and practice are discussed.     

Sequential asymmetric auctions with endogenous participation

In this paper we suggest a model of sequential auctions with endogenous participation where each bidder conjectures about the number of participants at each round. Then, after learning his value, each bidder decides whether or not to participate in the auction. In the calculation of his expected value, each bidder uses his conjectures about the number of participants for each possible subgroup. In equilibrium, the conjectured probability is compatible with the probability of staying in the auction. In our model, players face participation costs, bidders may buy as many objects as they wish and they are allowed to drop out at any round. Bidders can drop out at any time, but they cannot come back to the auction. In particular we can determine the number of participants and expected prices in equilibrium. We show that for any bidding strategy, there exists such a probability of staying in the auction. For the case of stochastically independent objects, we show that in equilibrium every bidder who decides to continue submits a bid that is equal to his value at each round. When objects are stochastically identical, we are able to show that expected prices are decreasing.     

Decomposing Bayesian networks: triangulation of the moral graph with genetic algorithms

In this paper we consider the optimal decomposition of Bayesian networks. More concretely, we examine empirically the applicability of genetic algorithms to the problem of the triangulation of moral graphs. This problem constitutes the only difficult step in the evidence propagation algorithm of Lauritzen and Spiegelhalter (1988) and is known to be NP-hard (Wen, 1991). We carry out experiments with distinct crossover and mutation operators and with different population sizes, mutation rates and selection biasses. The results are analysed statistically. They turn out to improve the results obtained with most other known triangulation methods (Kjærulff, 1990) and are comparable to results obtained with simulated annealing (Kjærulff, 1990; Kjærulff, 1992).     

Democratic transitions and the semiperiphery of the world-economy

The dramatic global transition to democracy of the last decade reveals important systematic patterns. Using recent contributions to world-systems theory, this study examines the relationship between political regime changes and the position of nations in the world-economy over the last two decades, to argue that democratic transitions have been centered among semiperipheral nations. The study also found a strong relationship between the structure of the labor force and the global distribution of democratic institutions, but a weak relationship between the structure of the labor force and the timing of transitions in the semiperiphery. Overall, the findings suggest that world-systemic categories provide a useful vantage point to distinguish global trends from the specific characteristics of individual nations, thereby allowing for greater analytical precision in identifying the crucial causal relations shaping transitions from dictatorship to democracy.     

A class of log-linear models with constrained marginal distributions

Summary In the log-linear model for bivariate probability functions the conditional and joint probabilities have a simple form. This property make the log-linear parametrization useful when modeling these probabilities is the focus of the investigation. On the contrary, in the log-linear representation of bivariate probability functions, the marginal probabilities have a complex form. So the log-linear models are not useful when the marginal probabilities are of particular interest. In this paper the previous statements are discussed and a model obtained from the log-linear one by imposing suitable constraints on the marginal probabilities is introduced. This work was supported by a M.U.R.S.T. grant.     

Threshold Cointegration and the PPP Hypothesis

Self-Exciting Threshold Autoregressive (SETAR) models are a non-linear variant of conventional linear Autoregressive (AR) models. One advantage of SETAR models over conventional AR models lies in its flexible nature in dealing with possible asymmetric behaviour of economic variables. The concept of threshold cointegration implies that the Error Correction Mechanism (ECM) at a particular interval is inactive as a result of adjustment costs, and active when deviations from equilibrium exceed certain thresholds. For instance, the presence of adjustment costs can, in many circumstances, justify the fact that economic agents intervene to recalibrate back to a tolerable limit, as in the case when the benefits of adjustment are superior to its costs. We introduce an approach that accounts for potential asymmetry and we investigate the presence of the relative version of the purchasing power parity (PPP) hypothesis for 14 countries. Based on a threshold cointegration adaptation of the unit root test procedure suggested by Caner & Hansen (2001), we find evidence of an asymmetric adjustment for the relative version of PPP for eight pairs of countries.     

A general maximum likelihood analysis of measurement error in generalized linear models

This paper describes an EM algorithm for maximum likelihood estimation in generalized linear models (GLMs) with continuous measurement error in the explanatory variables. The algorithm is an adaptation of that for nonparametric maximum likelihood (NPML) estimation in overdispersed GLMs described in Aitkin (Statistics and Computing 6: 251–262, 1996). The measurement error distribution can be of any specified form, though the implementation described assumes normal measurement error. Neither the reliability nor the distribution of the true score of the variables with measurement error has to be known, nor are instrumental variables or replication required.Standard errors can be obtained by omitting individual variables from the model, as in Aitkin (1996).Several examples are given, of normal and Bernoulli response variables.     

The Influence of The People of Puerto Rico Project on Mexican Anthropology

In the 1970s in Mexico, anthropological regional projects were designed to explore new research interests: irrigation works, peasants, rural capitalism, and mines. Julian H. Steward, Eric R. Wolf, and Sidney W. Mintz, participants in the research project on Puerto Rico, were all popular authors among the new generation of anthropologists and were frequently cited in their thesis bibliographies. This article explores the influence of the People of Puerto Rico project at the design level of these new collective and regional projects. Students were distributed within larger areas, covering various climatic and production subareas, in their research training. The important role of cities, industries, haciendas, markets, and government programs was highlighted. I suggest that senior anthropologists and academic leaders who were planning this new anthropological era were more familiar than their students with the conceptual lines of the Puerto Rico Project. I gained greater insight into the difficulties of a regional research enterprise when I did anthropological research in the 1980s at the Tennessee Valley project.     

Identity status differences among Italian adolescents: Associations with time perspective

Based on Marcia's identity status model, this cross-sectional study examined adolescents' identity formation analyzing its association with time perspective. A sample of 1300 Italian adolescents filled in self-report measures assessing two major developmental processes: identity resolution and time perspective. Adolescents who achieved an integrated identity status seemed to primarily adopt a future time perspective and to have a positive view of the past. By contrast, Diffused adolescents reported negative experiences in the past, a lower future orientation and a greater inclination to fatalism compared to others.