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991.
A simple summary of a treatment effect is attractive, which is part of the explanation of the success of the Cox model when analysing time‐to‐event data since the relative risk measure is such a convenient summary measure. In practice, however, the Cox model may fail to give a reasonable fit, very often because of time‐changing treatment effect. The Aalen additive hazards model may be a good alternative as time‐changing effects are easily modelled within this model, but results are then evidently more complicated to communicate. In such situations, the odds of concordance measure (OC) is a convenient way of communicating results, and recently Martinussen & Pipper (2012) showed how a variant of the OC measure may be estimated based on the Aalen additive hazards model. In this study, we propose an estimator that should be preferred in observational studies as it always estimates the causal effect on the chosen scale, only assuming that there are no un‐measured confounders. The resulting estimator is shown to be consistent and asymptotically normal, and an estimator of its limiting variance is provided. Two real applications are provided. 相似文献
992.
This paper evaluates the ability of a Markov regime-switching log-normal (RSLN) model to capture the time-varying features of stock return and volatility. The model displays a better ability to depict a fat tail distribution as compared with using a log-normal model, which means that the RSLN model can describe observed market behavior better. Our major objective is to explore the capability of the model to capture stock market behavior over time. By analyzing the behavior of calibrated regime-switching parameters over different lengths of time intervals, the change-point concept is introduced and an algorithm is proposed for identifying the change-points in the series corresponding to the times when there are changes in parameter estimates. This algorithm for identifying change-points is tested on the Standard and Poor's 500 monthly index data from 1971 to 2008, and the Nikkei 225 monthly index data from 1984 to 2008. It is evident that the change-points we identify match the big events observed in the US stock market and the Japan stock market (e.g., the October 1987 stock market crash), and that the segmentations of stock index series, which are defined as the periods between change-points, match the observed bear–bull market phases. 相似文献
993.
Poduri S.R.S. Rao 《统计学通讯:理论与方法》2013,42(15):1659-1669
The MINQUE and its modifications are considered for estimating the variances of the balanced one-way random effects model. The effects of the a priori values on the estimators of the variances are examined in detail. The Mean Square Errors of the estimators are compared for variations in the prior values of the unknown variances. 相似文献
994.
For a general class of continuous ( and marginally symmetric ) inultivariate distributions, based on suitable M-statistics ( involving bounded but possibly discontinuous score generating functions), shrinkage estimators of location are considered. These estimators are based on the James-Stein type rule and incorporates the idea of preliminary test estimation too. The main emphasis is laid on the study of asymptotic tdistributional ) risk properties of these est-innators, and asymptotic tin-) adraissibility results are also studied under fairly general regularity conditions. 相似文献
995.
M. C. Spruill 《统计学通讯:理论与方法》2013,42(9):3305-3312
A known number N of packages each contain, in differing unknown amounts, both substances of no particular import and some substance of interest, the total weight of the latter substance for all N of the packages being an unknown quantity T. Based on the amounts of the substance of interest found in each of n (n ≦= N) randomly sampled packages one is to decide, with a very small probability of the error of wrongly deciding that T exceeds L, whether or not the quantity T exceeds a given amount L. An optimal way of doing this is presented in which the probability of the error of wrongly deciding that T exceeds L can be precisely bounded above as desired. 相似文献
996.
为了向分布式实时嵌入式系统(DRES)的运行过程提供可信保障服务,方便上层应用程序的开发,提出了一种针对DRES的可信构件服务模型QUOCCM。该模型将系统功能实现与性能确保分离开,把应用程序的性能确保模块抽象成通用的服务确保构件,为运行于动态环境下的应用程序提供自适应的可信保障服务。该文以一个模拟实现的飞行控制系统验证了QUOCCM模型的可行性和灵活性。 相似文献
997.
用固体的Einstein模型与Debye模型分别导出相应模型的固气相变的蒸发热和蒸发压公式,并对其做数值计算。结果表明,蒸发热与温度之间近似呈线性关系,之与工程上经验近似是一致的。 相似文献
998.
The stage gate model has been proposed for application to uncertain technology development. Reports on industrial experience from such implementations are quite limited, however. This led us to explore in six companies what adaptations have been made to facilitate the model's usefulness for technology development and the companies’ experiences from their practical application of the model. Our results indicate that aspects proven important for the operational success, or failure, of the model include the level of adaptation to the characteristics of technology development and a more flexible use than that normally found in product development. 相似文献
999.
This paper identifies interrelationships between evidence-based practice (EBP), radical structuralism, and culture, arguing that culturally-specific beliefs and norms should be integrated into evidence-based, cross-cultural partnerships within child and family service systems. A single case study of family advocate training in evidence-based practice is provided as an illustration of, and impetus for, the development of a format for use with community-based and ethnically-diverse parent/family advocates. The lessons learned from teaching evidence-based practice to a parent advocate in a particular child welfare service system are highlighted. The use of enhanced roles for social workers and indigenous social capital and resources, such as family advocates as allies, is recommended to help achieve a greater degree of accountability, cooperation, and core understanding in the use of EBP. By training racially-diverse foster parents as mental health advocates to work collaboratively with policymakers, community groups, and family participants, proponents of EBP will reach and benefit more diverse populations. 相似文献
1000.
The Nordic welfare states offer some lessons in a development context. A main achievement has been sustainable poverty reduction. Another important lesson is that, while democratization often leads to greater pressures for social policy expansion, social policy can also contribute to democratization. The Nordic countries further demonstrate that is possible to unify social protection with a competitive and growth-oriented economy. In a number of policy areas, particularly in relation to social services and labor market policy, the Nordic countries have also become leading modernizers. The women-friendly dual-earner model not only combats poverty among families with children, but also enables women to participate in the labor market. The future sustainability of the Nordic model of social policy hinges on the number of taxpayers that can be mobilized. In order to be successful in this, governments need to take a combined, or holistic, approach, and consider both micro motives and macro considerations. 相似文献