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941.
The authors define a class of “partially linear single‐index” survival models that are more flexible than the classical proportional hazards regression models in their treatment of covariates. The latter enter the proposed model either via a parametric linear form or a nonparametric single‐index form. It is then possible to model both linear and functional effects of covariates on the logarithm of the hazard function and if necessary, to reduce the dimensionality of multiple covariates via the single‐index component. The partially linear hazards model and the single‐index hazards model are special cases of the proposed model. The authors develop a likelihood‐based inference to estimate the model components via an iterative algorithm. They establish an asymptotic distribution theory for the proposed estimators, examine their finite‐sample behaviour through simulation, and use a set of real data to illustrate their approach.  相似文献   
942.
Timing of first fatherhood was examined in a sample of 206 at-risk, predominantly White men, followed prospectively for 17 years. An event history analysis was used to test a model wherein antisocial behavior, the contextual and familial factors that may contribute to the development of antisocial behavior, and common correlates of such behavior, including academic failure, substance use, and early initiation of sexual behaviors, lead both directly and indirectly to an early transition to fatherhood. Having a mother who was younger at first birth, low family SES, poor academic skills, failure to use condoms, and being in a cohabitating or marital relationship predicted entry into fatherhood. Implications of the findings for prevention of and intervention with early fathering are discussed.  相似文献   
943.
944.
945.
Abstract Research has thoroughly documented how out‐migration of the educated and skilled from rural areas leaves behind a poorer population and creates pockets of rural poverty. Recently, studies have recognized that the poor are also geographically mobile and that poverty migration patterns can reinforce rural poverty concentrations. In this process, certain impoverished rural communities in economically depressed regions receive a disproportionate share of poverty migrants, concentrating poverty in certain locations. This paper examines the conditions and processes through which poor rural communities become likely destinations for a highly mobile segment of the rural poor and near‐poor. Utilizing case studies of depressed rural Illinois communities, it investigates how the interplay of community factors and the behavior of migrants transforms rural communities from residentially stable to highly mobile, impoverished places.  相似文献   
946.
947.
We consider the problem of statistical inference on the parameters of the three parameter power function distribution based on a full unordered sample of observations or a type II censored ordered sample of observations. The inference philosophy used is the theory of structural inference. We state inference procedures which yield inferential statements about the three unknown parameters. A numerical example is given to illustrate these procedures. It is seen that within the context of this example the inference procedures of this paper do not encounter certain difficulties associated with classical maximum likelihood based procedures. Indeed it has been our numerical experience that this behavior is typical within the context of that subclass of the three parameter power function distribution to which this example belongs.  相似文献   
948.
The aim of this article is to shed some light on how strategic decisions and actions occur in organizations. The fundamental argument is that the traditional literature fails to provide an adequate understanding of how such decisions are made and that a new focus is needed. Drawing on organizational theory, the author approaches a new focus on decision-making, having the first described the traditional approaches.  相似文献   
949.
Abstract This study examines variation in filial responsibility expectations-the extent to which adult children are expected to assist and care for their aging parents-among a sample of 440 older persons. The analysis focuses on the relationship of filial responsibility expectations to residential location and tests the hypothesis that older rural residents have higher expectations for assistance from their children than do older urbanites. Current residential location is found to have little impact on expectations, but older persons who were raised in rural areas, particularly on farms, have significantly higher expectations for filial assistance than do older persons from urban backgrounds. Possible consequences of these patterns for the transmission of expectations from parents to children are discussed.  相似文献   
950.
This paper first introduces a parametric model for the generation of stationary random correlated binary sequences. The parameters of the model include the probability that a pixel is a binary one pixel and the length of the structuring element which dilates the initially spatially uncorrelated sequence. The spatial statistics of such eroded, dilated, opened and closed correlated binary sequences are derived in terms of the spatial statistics of the input binary sequence. Understanding of such one-dimensional processing is a precondition for understanding what happens in the more interesting two- dimensional case.  相似文献   
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