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111.
Previous research shows that living in a non-intact family is associated with educational disadvantages. This paper compares the relationships between childhood family structure, schooling, and earnings in Sweden and the USA. This comparison is interesting because both family structure and public policies differ significantly. We find a negative relationship between living in a non-intact family and child outcomes, and the estimates are remarkably similar in both countries. After using sibling-difference models, the correlation with family structure is no longer significant. These results cast doubt on the causal interpretation of the negative relationship between non-intact family structures and child outcomes.  相似文献   
112.
In sequential studies, formal interim analyses are usually restricted to a consideration of a single null hypothesis concerning a single parameter of interest. Valid frequentist methods of hypothesis testing and of point and interval estimation for the primary parameter have already been devised for use at the end of such a study. However, the completed data set may warrant a more detailed analysis, involving the estimation of parameters corresponding to effects that were not used to determine when to stop, and yet correlated with those that were. This paper describes methods for setting confidence intervals for secondary parameters in a way which provides the correct coverage probability in repeated frequentist realizations of the sequential design used. The method assumes that information accumulates on the primary and secondary parameters at proportional rates. This requirement will be valid in many potential applications, but only in limited situations in survival analysis.  相似文献   
113.
The technical characteristics of electricity generation and transmission have implications for the way in which economic principles are adapted to evaluate pricing and regulation issues in electricity markets. In particular, there is an externality associated with the way in which electricity flows in networks because of Kirchoff's laws. In this paper, a mathematical programming model is presented that simulates a competitive electricity market, based on the spatial-intertemporal equilibrium models pioneered by Takayama and Judge (1971). The model is used to simulate the operation of a hypothetical electricity market, illustrating some of the issues arising from the network externality.  相似文献   
114.
Cohabitation in Great Britain: not for long, but here to stay   总被引:2,自引:1,他引:1  
This paper uses a new source of data to study the dramatic increase in cohabiting unions in Great Britain. It analyses, in turn, entry into first partnership, the stability of cohabiting unions and repartnering after dissolution of cohabitation. In excess of 70% of first partnerships are now cohabitations, and these last a relatively short time before being either turned into marriage or dissolved. The shift to cohabitation as the dominant mode of first partnership plays an important role in the delay of first marriage and motherhood. The paper also investigates the factors that are associated with the outcome of cohabitations.  相似文献   
115.
Unmet need for family planning has been a core concept in international population discourse for several decades. This article reviews the history of unmet need and the development of increasingly refined methods of its empirical measurement and delineates the main questions that have been raised about unmet need during the past decade, some of which concern the validity of the concept and others its role in policy debates. The discussion draws heavily on empirical research conducted during the 1990s, much of it localized, in‐depth studies combining quantitative and qualitative methodologies. Of the causes of unmet need other than those related to access to services, three emerge as especially salient: lack of necessary knowledge about contraceptive methods, social opposition to their use, and health concerns about possible side effects. The article argues that the concept of unmet need for family planning, by joining together contraceptive behavior and fertility preferences, encourages an integration of family planning programs and broader development approaches to population policy. By focusing on the fulfillment of individual aspirations, unmet need remains a defensible rationale for the formulation of population policy and a sensible guide to the design of family planning programs.  相似文献   
116.
资本主义经济危机与周期的理论 ,是马克思主义政治经济学中固有的理论。对这一理论的研究 ,已逐渐延伸到对社会经济发展过程中一般周期性波动问题的探讨。人类经济的发展 ,是否也呈现一定的周期性 ?本文试图说明 ,人类经济历史发展过程 ,是沿着某种曲折的波形路径推进的  相似文献   
117.
    
Summary ‘Predator-foolhardiness’ (Lloyd andDybas, 1966b) in an epidemic population of the sugarcane cicada,Mogannia minuta was tested by counting the number of successful and failed trials of hand-capturing of adults in the centre and periphery of a heavily infested area. Males frequently failed to escape from capture in the outbreak area but they did not in the peripheral zone. Females could escape well irrespective of the density. It was considered that the ‘predator-foolhardiness’ of males is not due to genetic differentiation through the process of outbreak but to the effect of massive chorus on the escape behaviour. The work was supported in part by Grant-in-Aid No. 439017 from the Ministry of Education, Science and Culture.  相似文献   
118.
This paper reviews earlier research and presents new analytical findings regarding the outcomes of social movements. Using the resource mobilization/management approach, empirical propositions that seek to explain protest group success or failure are tested. Based upon data gathered from a sample of 53 US protest groups, the causal models explained the majority of the variance in degree of success between these groups. Our findings indicate that protest groups which threaten to replace or destroy established groups are usually unsuccessful, and those having many strong alliances tend to be more successful than groups fighting alone. The use of violence does not greatly aid the prediction of group outcome because of the unpredictable, ambivalent reaction to violence by established groups.  相似文献   
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