Summary For technological applications it can be useful to identify some simple physical mechanisms, which, on the basis of the available
knowledge of the production process, may suggest the most appropriate approach to statistical control of the random quantities
of interest. For this purpose the notion of rupture point is introduced firstly. A rupture point is characterized bym randomly arising out of control states, assumed to be mutually exclusive and stochastically independent. Shewhart's control
charts seem to represent the natural statistical tool for controlling a rupture point; however it is shown that they are fully
justified only when the hazard rates attached to the causes of failure are constant. Otherwise, typically in the presence
of time increasing hazard rates, Shewhart's control charts should be completed by a preventive intervention rule (preventive
maintenance). In the second place, the notion of dynamic instability point is introduced, which is specifically characterized
by assuming that the random quantity of interest is ruled by a stochastic differential equation with constant coefficients.
By discretization, developed according to a possibly new approach, it is shown that the former model reduces to an equation
error model, which is among the simplest used in adaptive control, and thus particularly easy to deal with in regard to parameter
estimation and the definition of the optimum control rule. 相似文献
We study, from the standpoint of coherence, comparative probabilities on an arbitrary familyE of conditional events. Given a binary relation ·, coherence conditions on · are related to de Finetti's coherent betting system: we consider their connections to the usual properties of comparative probability and to the possibility of numerical representations of ·. In this context, the numerical reference frame is that of de Finetti's coherent subjective conditional probability, which is not introduced (as in Kolmogoroff's approach) through a ratio between probability measures.Another relevant feature of our approach is that the family & need not have any particular algebraic structure, so that the ordering can be initially given for a few conditional events of interest and then possibly extended by a step-by-step procedure, preserving coherence. 相似文献
Previous empirical literature on the relation between intergenerational transfer of assets and services has mostly focused on contemporary exchanges. By contrast, we provide novel evidence showing that parents who helped their adult children in the past are rewarded by higher chances of receiving informal care later in life. To this end we use Italian data containing precise retrospective information about the help with housing that couples received from their parents when they got married, such as a real estate donation or down payment. Our estimates show that this type of past help is positively associated with the current provision of informal care to the parents. This result is robust to controlling for a large set of individual and family characteristics and is only partially due to increased geographical proximity. We suggest that this finding can be explained by mixed self-interest motives, related to theories based on either bilateral exchange or the presence of a third generation (grandchildren), such as the demonstration effect model or the family constitution model. 相似文献
Empirical studies have documented a decline in indicators of social participation in the last five decades. The responsibility of social disengagement has often been attributed to pervasive busyness and the increasing pressure on time. In this paper we argue that computer-mediated interaction, and particularly online networking, can help mitigate this downward trend. We develop a logical framework for assessing the role of the Internet in the evolution of social participation. We analyze an economy where agents can develop their social interactions through two main modes of participation, one encompassing both online networking and face to face interactions, and the other solely based on physical encounters. We study the interdependence between the increase in the pressure on time and the variation in the relative performance of the two strategies of participation. 相似文献
As known, the least-squares estimator of the slope of a univariate linear model sets to zero the covariance between the regression residuals and the values of the explanatory variable. To prevent the estimation process from being influenced by outliers, which can be theoretically modelled by a heavy-tailed distribution for the error term, one can substitute covariance with some robust measures of association, for example Kendall's tau in the popular Theil–Sen estimator. In a scarcely known Italian paper, Cifarelli [(1978), ‘La Stima del Coefficiente di Regressione Mediante l'Indice di Cograduazione di Gini’, Rivista di matematica per le scienze economiche e sociali, 1, 7–38. A translation into English is available at http://arxiv.org/abs/1411.4809 and will appear in Decisions in Economics and Finance] shows that a gain of efficiency can be obtained by using Gini's cograduation index instead of Kendall's tau. This paper introduces a new estimator, derived from another association measure recently proposed. Such a measure is strongly related to Gini's cograduation index, as they are both built to vanish in the general framework of indifference. The newly proposed estimator is shown to be unbiased and asymptotically normally distributed. Moreover, all considered estimators are compared via their asymptotic relative efficiency and a small simulation study. Finally, some indications about the performance of the considered estimators in the presence of contaminated normal data are provided. 相似文献
Increasingly, mental health and medical professionals have been asked to assess claims of psychological harm arising from harassment at the workplace, or "mobbing." This study assessed the personality and psychopathological profiles of 146 individuals exposed to mobbing using validity, clinical, and content scales of the Minnesota Multiphasic Personality Inventory 2. Profiles and factor analyses were obtained. Two major dimensions emerged among those exposed to mobbing: (a) depressed mood, difficulty in making decisions, change-related anguish, and passive-aggressive traits (b) somatic symptoms, and need for attention and affection. This cross-sectional pilot study provides evidence that personality profiles of mobbing victims and psychological damage resulting from mobbing may be evaluated using standardized assessments, though a longitudinal study is needed to delineate cause-and-effect relationships. 相似文献
Cet article traite, en premier lieu, du problème de la définition d'une méthode d'enquête, appropriée à l'analyse et à la compréhension de la réalité sociale. Il le fait en partant de la critique du modèle cognitiviste-comportementaliste que l'on peut relier aux noms de Boudon et Weber. Les intérêts, mais aussi et surtout les carences de ce modèle sont mis en évidence. Etant donné qu'il occupe, parmi les schémas méthodologiques apprêtés à la recherche sociologique, une place d'honneur pour sa rigueur et sa fécondité analytique, ses carences soulignent avec une clarté particulière non seulement les difficultés que la pensée sociale rencontre dans le domaine de la méthode, mais aussi les conséquences négatives de celles-ci sur la scientificité de l’élaboration théorique, entendue comme la capacité à interpréter et à expliquer la réalité de référence.
La critique de l’élaboration de R. Boudon sur la méthode aide aussi à mettre en évidence, par contraste, les motifs, les caractéristiques et les potentialités de notre proposition méthodologique, qui est présentée tout de suite après. Sur la base de cette proposition, que nous appelons objectivisme social, nous avons formulé non seulement des objections au relativisme culturel de Weber et à l'anti-relativisme culturel et cognitif de R. Boudon, mais aussi à la notion de rationalité et à la théorie sur l’évolution sociale de ce dernier auteur.
Parallèlement, sont proposées une notion de rationalité différente et une explication alternative des processus sociaux, laquelle embrasse des aspects concernant tant l’évolution que l'organisation des sociétés humaines et qui peut être facilement étendue aussi à l'interprétation des processus historiques. 相似文献
Under the pressure of population aging the Italian pension system has undergone reforms to increase labor force participation and retirement age, and, thus, the length of working life. However, how the duration of working life has developed in recent years is not well understood. This paper is the first to analyze trends in working life expectancy in Italy. We use data from a nationally representative longitudinal sample of 880,000 individuals from 2003 to 2013 and estimate working life expectancy by gender, occupational category, and region of residence using a Markov chain approach. We document large and increasing heterogeneity in the length of working life. From 2003–2004 to 2012–2013, working life expectancy for men declined from 35.2 to 27.2 years and for women from 34.7 to 23.7 years, increasing the gender gap to 3.5 years. Both young and old were hit, as roughly half of the decline was attributable to ages below 40, half above 40. Working life expectancy declined for all occupational groups, but those in manual occupations lost most, 8.5 years (men) and 10.5 years (women). The North–South economic gradient widened such that men living in the North were expected to work 8 years longer than women living in the South. The fraction of working life of total life expectancy at age 15 declined to record lows at 40% for men and 34% for women in 2012–2013. Policies aiming at increasing total population working life expectancy need to take into consideration the socio-demographic disparities highlighted by our results.
ABSTRACTResidential care is one of the most restrictive out-of-home care settings; however, this is a temporary placement and youth eventually reintegrate into the home and community setting. Reintegration presents many challenges, and aftercare becomes critical for maintaining youth gains and promoting family stability. Aftercare programs and supports should align to individual family needs that entail understanding individual and familial characteristics. Previous studies have explored characteristics related to family functioning, mental health, behavior, and perceptions of need during reintegration; yet little is known regarding how affective characteristics (i.e., self-efficacy, empowerment) factor into reintegration, or the implications this may have for providers. The purpose of this study was to address this gap by exploring empowerment and self-efficacy in caregivers (N = 120) who had a child return home within 1 month of departing residential care. Overall, caregivers reported high levels of empowerment and self-efficacy during the initial transition period. Significant differences for empowerment and self-efficacy were present in characteristics such as race, income, number of children in the home, and free/reduced lunch status. 相似文献