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951.
In this article, we introduce three new distribution-free Shewhart-type control charts that exploit run and Wilcoxon-type rank-sum statistics to detect possible shifts of a monitored process. Exact formulae for the alarm rate, the run length distribution, and the average run length (ARL) are all derived. A key advantage of these charts is that, due to their nonparametric nature, the false alarm rate (FAR) and in-control run length distribution is the same for all continuous process distributions. Tables are provided for the implementation of the charts for some typical FAR values. Furthermore, a numerical study carried out reveals that the new charts are quite flexible and efficient in detecting shifts to Lehmann-type out-of-control situations. 相似文献
952.
953.
The variational approach to Bayesian inference enables simultaneous estimation of model parameters and model complexity. An interesting feature of this approach is that it also leads to an automatic choice of model complexity. Empirical results from the analysis of hidden Markov models with Gaussian observation densities illustrate this. If the variational algorithm is initialized with a large number of hidden states, redundant states are eliminated as the method converges to a solution, thereby leading to a selection of the number of hidden states. In addition, through the use of a variational approximation, the deviance information criterion for Bayesian model selection can be extended to the hidden Markov model framework. Calculation of the deviance information criterion provides a further tool for model selection, which can be used in conjunction with the variational approach. 相似文献
954.
For regression on state and transition probabilities in multi-state models Andersen et al. (Biometrika 90:15–27, 2003) propose
a technique based on jackknife pseudo-values. In this article we analyze the pseudo-values suggested for competing risks models
and prove some conjectures regarding their asymptotics (Klein and Andersen, Biometrics 61:223–229, 2005). The key is a second
order von Mises expansion of the Aalen-Johansen estimator which yields an appropriate representation of the pseudo-values.
The method is illustrated with data from a clinical study on total joint replacement. In the application we consider for comparison
the estimates obtained with the Fine and Gray approach (J Am Stat Assoc 94:496–509, 1999) and also time-dependent solutions
of pseudo-value regression equations. 相似文献
955.
In this paper we consider a sequential design for the estimation of nonlinear parameters of regression with guaranteed accuracy. Non-asymptotic confidence regions with fixed sizes for the least squares estimates are used. The obtained confidence region is valid for finite numbers of data points when the distributions of the observations are unknown. 相似文献
956.
A onestep estimator, which is an approximation to the unconditional maximum likelihood estimator (MLE) of the coefficient matrices of a Gaussian vector autoregressive process is presented. The onestep estimator is easy to compute and can be computed using standard software. Unlike the computation of the unconditional MLE, the computation of the onestep estimator does not require any iterative optimization and the computation is numerically stable. In finite samples the onestep estimator generally has smaller mean square error than the ordinary least squares estimator. In a simple model, where the unconditional MLE can be computed, numerical investigation shows that the onestep estimator is slightly worse than the unconditional MLE in terms of mean square error but superior to the ordinary least squares estimator. The limiting distribution of the onestep estimator for processes with some unit roots is derived. 相似文献
957.
While it is well known that the widowed suffer increased mortality risks, the mechanism of this survival disadvantage is still
under investigation. In this article, we examine the quality of health care as a possible link between widowhood and mortality
using a unique data set of 475,313 elderly couples who were followed up for up to nine years. We address whether the transition
to widowhood affects the quality of care that individuals receive and explore the extent to which these changes mediate the
elevated mortality hazard for the widowed. We analyze six established measures of quality of health care in a fixed-effect
framework to account for unobserved heterogeneity. Caregiving and acute bereavement during the transition to widowhood appear
to distract individuals from taking care of their own health care needs in the short run. However, being widowed does not
have long-term detrimental effects on individuals’ ability to sustain contact with the formal medical system. Moreover, the
short-run disruption does not mediate the widowhood effect on mortality. Nevertheless, long after spousal death, men suffer
from a decline in the quality of informal care, coordination between formal and informal care, and the ability to advocate
and communicate in formal medical settings. These findings illustrate women’s centrality in the household production of health
and identify important points of intervention in optimizing men’s adjustment to widowhood. 相似文献
958.
Kevin J. A. Thomas 《Demography》2009,46(3):513-534
In this study, I examine disparities in schooling progress among children born to immigrant and U.S.-born blacks. I find that
in one- and two-parent families, children born to black immigrants are less likely to fall behind in school than those born
to U.S.-born blacks. In two-parent immigrant families, children born to two immigrant parents have a significant schooling
advantage over children born to one immigrant parent. While children born to two immigrant parents in the wealthiest black
immigrant families do better in the second generation than in the first, the reverse is observed among children in less wealthy
families. These findings contribute in two ways to our understanding of the assimilation processes of children born to black
immigrant parents. First, they show that there is a positive association between the number of immigrant parents in a family
and children’s schooling performance. Second, they suggest that disparities in the assimilation patterns of the children of
black immigrants are a likely product of the interaction between their parental characteristics and the socioeconomic circumstances
of their families. 相似文献
959.
P. L. Rika Fatimah A. A. Jemain K. Ibrahim S. Mohammad Nasir M. A. Khairul Anuar 《Social indicators research》2009,92(1):131-149
Determining priority importance is a matter of concerns among the organization to improve their performance. One of the important
aspects that should be considered by the organization is management of human resources, comprising of members who have their
own family life. In this paper, we deliver a new perspective for organization to provide priority importance for their members
with respect to family matters in order to inculcate the sense of belonging in the organization. To be effective in considering
family matters in the organizational policy making, closer look of family characteristics are required. The idea of translating
several family characteristics as quality variables and applying the quality function deployment (QFD) method to these variables
could present a new way of improving the decision making in the organization by considering the process of decision in the
family. Quality function deployment for family (QFDF) produces a friendly interpretation of a highly complex and intangible
matters around family life; thus, making the assessment of a family easier. QFD is applied on the data gathered from a questionnaire
survey based on 1,213 families in West Malaysia, Malaysia. Twelve variables are identified as voice of family, where seven
of them are found to have the highest priority of importance. These variables could also be translated into quality variables
in the context of organization, the strategy of improvement for the family could be interpreted as strategy for improvement
in the organization. Furthermore, the results of this study provide suggestion to improve actions for managing human resource.
In the discussion, three most high ranked variables from both perspectives of family and organization are considered. 相似文献
960.