Migration as a Family Business: The Role of Personal Networks in the Mobility Phase of Migration

Formulée pour la première fois par John Salt et Jeremy Stein dans International Migration en 1997, la conception de la migration en tant qu'activité commerciale a transformé la perception de ce phénomène aussi bien auprès des spécialistes que des médias grand public. Cependant, bien que ce modèle propose un nouvel outil utile pour étudier les déplacements des individus dans le monde, sa popularité en tant que métaphore a eu pour conséquence d'occulter d'autres aspects du sujet qu'il n'arrivait pas à intégrer. Comme l'auteur cherche à le démontrer par l'analyse d'entretiens avec des migrants du Maroc et du Sénégal en Espagne et d'Egypte et du Ghana en Italie ainsi que par les profils de divers migrants aux Pays-Bas, la métaphore de l'activité commerciale n'apporte qu'une réponse partielle. Elle ne permet pas d'expliquer l'importance primordiale que revêtent pour la plupart des migrants les réseaux d'amis, de parents et de connaissances au moment d'entreprendre leur voyage.     

STENO:an expert system for medical diagnosis based on graphical models and model search

Causal probabilistic models have been suggested for representing diagnostic knowledge in expert systems. This paper describes the theoretical basis for and the implementation of an expert system based on causal probabilistic networks. The system includes model search for building the knowledge base, a shell for making the knowledge base available for users in consultation sessions, and a user interface. The system contains facilities for storing knowledge and propagating new knowledge, and mechanisms for building the knowledge base by semi-automated analysis of a large sparse contingency table. The contingency table contains data acquired for patients in the same diagnostic category as the intended application area of the expert system. The knowledge base of the expert system is created by combining expert knowledge and a statistical model search in a model conversion scheme based on a theory developed by Lauritzen & Spiegelhalter and using exact tests as suggested by Kreiner. The system is implemented on a PC and has been used to simulate the diagnostic value of additional clinical information for coronary artery disease patients under consideration for being referred to coronary arteriography.     

Estimation of binomial parameters when both , are unknown

We revisit the classic problem of estimation of the binomial parameters when both parameters n,p are unknown. We start with a series of results that illustrate the fundamental difficulties in the problem. Specifically, we establish lack of unbiased estimates for essentially any functions of just n or just p. We also quantify just how badly biased the sample maximum is as an estimator of n. Then, we motivate and present two new estimators of n. One is a new moment estimate and the other is a bias correction of the sample maximum. Both are easy to motivate, compute, and jackknife. The second estimate frequently beats most common estimates of n in the simulations, including the Carroll–Lombard estimate. This estimate is very promising. We end with a family of estimates for p; a specific one from the family is compared to the presently common estimate and the improvements in mean-squared error are often very significant. In all cases, the asymptotics are derived in one domain. Some other possible estimates such as a truncated MLE and empirical Bayes methods are briefly discussed.     

New tests for stochastic order with application to case control studies

It is shown that if a binary regression function is increasing then retrospective sampling induces a stochastic ordering of the covariate distributions among the responders, which we call cases, and the non-responders, which we call controls. We also show that if the covariate distributions are stochastically ordered then the regression function must be increasing. This means that testing whether the regression function is monotone is equivalent to testing whether the covariate distributions are stochastically ordered. Capitalizing on these new probabilistic observations we proceed to develop two new non-parametric tests for stochastic order. The new tests are based on either the maximally selected, or integrated, chi-bar statistic of order one. The tests are easy to compute and interpret and their large sampling distributions are easily found. Numerical comparisons show that they compare favorably with existing methods in both small and large samples. We emphasize that the new tests are applicable to any testing problem involving two stochastically ordered distributions.     

Binomial confidence limits adjusted for a confounding variable

A simple transformation of classical binomial confidence limits provides exact confidence limits in situations where a confounding variable is present. An example is the multiple-choice test, where a correct answer may represent either knowledge or guesswork, the latter being the confounding variable.     

The Effects of Misconceptions on the Properties of Friedman's Test

Friedman's test is a widely used rank-based alternative to the analysis of variance (ANOVA) F-test for identifying treatment differences in a randomized complete block design. Many texts provide incomplete or misleading information about when Friedman's test may be appropriately applied. We discuss the assumptions needed for the test and common misconceptions. We show via simulation that when the variance or skew of the treatment distributions differ, application of Friedman's test to detect differences in treatment location can result in Type I error probabilities larger than the nominal α, and even when α is unaffected, the power of the test can be less than expected.     

The fate of the sexually abused child

This article emphasizes the importance of understanding the specific meaning of sexual abuse to the particular child in his/her particular developmental stage. A critique of the research is presented, along with discussion of the psychodynamic impact of sexual abuse on the developing ego of the child. The primary means of adaptation following the trauma are (1) identification with the aggressor and (2) the repetition compulsion. It is also suggested that Freud's seduction theory can coexist with his later fantasy theory. Two case vignettes are presented to highlight the theoretical discussion.     

Occupational pursuits of free women in early America: An examination of eighteenth-century newspapers

The revival of social and family history during the past two decades has resulted in major revisions of conventional explanations of the processes of social change. Scholarship concerning the status, roles, and contributions of early American women has been especially important in this respect. This paper is based on original findings from a systematic survey of the occupational pursuits of early American women (N=2,572) and a stratified sample (N=1,949), both derived from eighteenth-century newspaper advertisements. Our findings focus on the distribution of occupations available to women, important trends during the period, and factors contributing to changes in the occupational structure of early America.