Estimation of a Change Point in a Hazard Function Based on Censored Data

The hazard function plays an important role in reliability or survival studies since it describes the instantaneous risk of failure of items at a time point, given that they have not failed before. In some real life applications, abrupt changes in the hazard function are observed due to overhauls, major operations or specific maintenance activities. In such situations it is of interest to detect the location where such a change occurs and estimate the size of the change. In this paper we consider the problem of estimating a single change point in a piecewise constant hazard function when the observed variables are subject to random censoring. We suggest an estimation procedure that is based on certain structural properties and on least squares ideas. A simulation study is carried out to compare the performance of this estimator with two estimators available in the literature: an estimator based on a functional of the Nelson-Aalen estimator and a maximum likelihood estimator. The proposed least squares estimator tums out to be less biased than the other two estimators, but has a larger variance. We illustrate the estimation method on some real data sets.     

社会与国家

拉吉切维奇(以下简称“拉”):近年来南斯拉夫舆论界对文明社会和法制国家的讨论越来越多。这些讨论一方面要求明确国家的职能,另一方面又要求恢复一定范围的私有制,并且国家不得干预。公众对首先出自斯洛文尼亚的上述思想尽管还持有疑虑,但由于该思想具有鼓动作用,依然赢得了越来越多的支持者。普尔比奇(以下简称“普”):文明社会概念近几年来确实成了克罗地亚和塞尔维亚政治言论中的时髦词。据我所知,克罗地亚-塞尔维亚语中的这一政治词汇是从斯洛文尼亚文直译     

奴隶制

一、奴隶制法学家佛罗伦提努斯曾将奴隶制界说为“一种据以使一个人处于另一个人支配之下的悖于天理的‘万民法’(ius gentium)制度”(《学说汇纂》1.5、4、1)。在非法学范围内,古人经常使用我们译之为“奴隶”一词(以及其词根绝非奴隶之意的词汇)的各种字眼,虽则并非出于粗心之故。其泛用程度远过于在法学范围中的使用。古希腊人的“奴隶”意义的词汇变化多端,他们在这方面的泛用尤为突出。他们往往将此等词汇泛用于诸如黑劳士之类的具有其他奴役关系的范畴中,而严格言之,黑劳士与其主人并无财产性关系。又如,在古典时代的希腊文中,“杜洛斯”(例如,与“安德拉波顿”比较)习用于对比自     

世界经济与第三世界的国家结构

16世纪产生于欧洲的资本主义世界经济,是在单一的劳动分工基础上联结起来的综合的生产过程网络,其基本经济规律是通过不断占有剩余价值而进行资本积累,这些剩余价值是通过原始积累、资本集中以及不平等交换等积聚起来的。它的政治上层建筑是包括主权和殖民地“国家”在内的国际体系。这一国际体系中的某些国家,在经济上从来就不是自主的。随着世界经济的发展,一些新的地区加入了世     

Migration patterns of the elderly: the case of the American Jewish population

"This article examines the growing concentration of the elderly Jewish population of the U.S. in one metropolitan region of the Sun Belt. The principal data sources used are U.S. Census counts of the population with a Yiddish mother tongue or speaking Yiddish at home, as well as 1980 data on the population of Russian ancestry. The limitations of these measures are discussed and data from local community surveys also are presented. The data show that relocation of the elderly from the North, especially to South Florida, has been occurring since the 1950s and accelerated during the 1970s. The need for further study, which may document the migration patterns of elderly members of diverse religions and ethnic groups, is pointed out."     

Occupational mobility among immigrants: the impact of migration on economic success in Australia

"By analyzing national survey data collected among immigrants to Australia, this article examines immigrant occupational mobility. For immigrants, the results show economic disadvantages are caused by the act of migration itself rather than by economic experiences in their new country. Occupational status is depressed at the beginning of the immigrants' Australian working career, and this in turn diminishes occupational status throughout the working lives of the immigrants and accounts for the economic disadvantages they face."     

The shift from vertical to networked integration, Part 1

Lessons, dangers, and difficulties for health care integrators from the world of mergers, acquisitions, and alliances. The authors examine why there needs to be a shift from vertical integration, with its command and control hierarchical structure, to the more fluid and flexible networked enterprise in health care. By sharing the integration experiences of other industries, the authors make a compelling case for rethinking the integrated delivery system that so many have embraced and explain why the emergence of the extended health care enterprise will be the next stage in the progression. Making the journey into networked enterprises--how to start, what to do, and case studies from St. Vincent's, Cascade Healthcare Alliance, and Mullikin Medical Centers--will be presented in the second article in the June 1996 issue of Physician Executive.     

Interethnic marriage: identifying the second generation in Australia

"Studies in Australia show that an increasing proportion of the population have ancestors from more than one country. Evidence regarding differences in the marriage patterns of first and second generation migrants has been restricted in scope as published marriage registration data includes only birthplace of partners. Marriage registration records include information about the birthplace of parents of partners, but is available only through specially produced tabulations. Changes in the census for 1986 and 1991 make it possible to identify the second generation in households, and this article examines the use of census data as an alternative to marriage registration records in tracing changes in intermarriage patterns and differences between urban and rural areas."     

DSM-IV and the South Oaks Gambling Screen: diagnosing and assessing pathological gambling in Turkey

The main purpose of this study was to investigate the effectiveness of the DSM-IV diagnostic criteria and the South Oaks Gambling Screen (SOGS) in identifying Turkish pathological gamblers. Fifty-nine subjects participated in the study. The subjects were diagnosed as either pathological gamblers or not (comparison group) through the use of the DSM-IV criteria and were given the Turkish version of the SOGS. Four of the ten DSM-IV criteria were found to be problematic in the diagnosis of Turkish pathological gamblers. The data concerning reliability and validity of the Turkish version of the SOGS suggested that the SOGS can be used as a reliable and valid instrument in identifying Turkish pathological gamblers. Most (16 out of 20) of the items of the SOGS appear to work well in discriminating pathological gamblers from the subjects in the comparison group. In the case of the two DSM-IV criteria and the four SOGS items that failed to discriminate, cultural factors seemed to be responsible for the failure.