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81.
Economic development and fertility change in Mexico, 1950–1970   总被引:1,自引:0,他引:1  
Hicks WW 《Demography》1974,11(3):407-421
This paper is an attempt to isolate the determinants of fertility in Mexico. Of the variables included, two are significant in accounting for differences in the level of completed fertility in the 32 "states" in 1970. They are the share of the labor force in agriculture, which is directly related to fertility, and the percentage of the population speaking an indigenous language, which shows an inverse relationship.The most important factors acting to reduce total fertility rates over time are increases in life expectancy and declines in the share of the labor force in agriculture. However, based on the estimated linear relationship, these two variables by themselves are not adequate to achieve a rapid decline in fertility in the future.  相似文献   
82.
83.
Using many moment conditions can improve efficiency but makes the usual generalized method of moments (GMM) inferences inaccurate. Two‐step GMM is biased. Generalized empirical likelihood (GEL) has smaller bias, but the usual standard errors are too small in instrumental variable settings. In this paper we give a new variance estimator for GEL that addresses this problem. It is consistent under the usual asymptotics and, under many weak moment asymptotics, is larger than usual and is consistent. We also show that the Kleibergen (2005) Lagrange multiplier and conditional likelihood ratio statistics are valid under many weak moments. In addition, we introduce a jackknife GMM estimator, but find that GEL is asymptotically more efficient under many weak moments. In Monte Carlo examples we find that t‐statistics based on the new variance estimator have nearly correct size in a wide range of cases.  相似文献   
84.
The intent of the current article is to describe the development of a new approach to the study of ethical conduct in scientific research settings. The approach presented in this article has two main components. The first component entails the development of a taxonomy of ethical events as they occur across a broad range of scientific disciplines. The second involves the identification of proximate criteria that will allow systematic and objective evaluation of ethical behaviors through low-fidelity performance simulations. Two proposed measures based on the new approach are intended to identify and measure variations in the scientific environment that might predispose certain individuals to make unethical decisions.  相似文献   
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86.
Abstract

Like all radical community endeavours, queer performance in the United States has been shaped through resistance to restrictive ideologies. National insecurity over ‘indecent’ (read: queer) artistic expression in the US has been aimed at artists working in a variety of genres, and here I focus specifically on queer solo performance artists. This essay explores the dangerous realities that queer artists present to an imagined unified US national identity. I argue that queer solo performers operate as artistic activists, challenging homogenous fantasies about US culture through the queering of experience. Aesthetically disparate, their work is connected by common threads of vulnerability and precarity. The article asks how their work disrupts U.S. insecurities concerning intersections of sexuality, gender identity, race and religion.  相似文献   
87.
Child homelessness and educational well-being is an area of national research that requires more precise investigation to address mixed findings. The aim of this study was to extend the investigation of the relations between homelessness and educational well-being by determining if timing and frequency of homeless episodes are differentially associated with children's academic and classroom engagement outcomes. This investigation used a comprehensive research model to study the effects of these homeless episode characteristics within a large urban student cohort. Additionally, this study accounted for co-occurring early risk factors. Findings indicated that having a first homeless episode in early childhood was associated with non-proficiency in mathematics and academic engagement problems. Also more frequent homeless episodes were related to truancy in third grade. These results stress the importance of early intervention for homeless children and underscore the need to further understand the variation in young children's homeless experiences.  相似文献   
88.
Women with substance abuse disorders typically have psychosocial characteristics that put them at risk for disrupted parenting. Prior research indicates that comprehensive, accessible services tailored to the mothers' needs can contribute to family stability. This study further explores the complicated interplay of how maternal risk and protective characteristics and service elements are associated with reunification. The study contributes to existing literature by following mothers for three years; examining service needs as identified by the mother herself; using a summary proportion score to reflect the totality of services received to matched service needs identified; and using logistic regression to examine interactions of services received with critical maternal characteristics. The sample is comprised of 458 substance-abusing mothers enrolled during pregnancy or postpartum in the Washington State Parent-Child Assistance Program (PCAP), an evidence-based case management intervention. Participants' custody status was well distributed among four categories based on continuity of parenting. Findings indicate that at program exit 60% of the mothers were caring for their index child. These mothers had more treatment and mental health service needs met, had more time abstinent from alcohol and drugs, secure housing, higher income, and support for staying clean and sober. Among women with multiple psychiatric diagnoses, the odds of regaining custody were increased when they completed substance abuse treatment and also had a supportive partner. Mothers who lost and did not regain custody had more serious psychiatric problems and had fewer service needs met. We discuss implications of our findings for child welfare policy and practices.  相似文献   
89.
Rushton's theory of r-K race differences was examined in relation to the rate of murder, rape, and serious assault per 100,000 population and Gross Domestic Product per Person for 74 countries from the 1993–1996 International Crime Statistics published by INTERPOL and the 1999 CIA World Fact Book. Each country was assigned to one of the three macro-races East Asian, European, and African. The results corroborated earlier findings that violent crime is lowest in East Asian countries, intermediate in European countries, and highest in African and in Black Caribbean countries. The median number of violent crimes per 100,000 population were: 7 East Asian countries—34; 45 European countries—42; and 22 African and Black Caribbean countries—149, respectively. The median Gross Domestic Product per Person was highest in East Asian countries ($12,600), intermediate in European countries ($7,400), and lowest in African and Black Caribbean countries ($1,900). Across the three population groups there was an ecological correlation of –.96 between crime and wealth (wealthier countries had less crime). Finer-grained analyses, however, found that while wealth was negatively related to crime across European or East Asian countries, it was positively related to crime for the African and Black Caribbean countries (i.e., the wealthier an African or Black Caribbean country, the greater its rate of violent crime). Future research needs to examine genetic factors in addition to cultural factors as well as their interactions.  相似文献   
90.
Often it is necessary to estimate the parameters of a model or unknown system. Various techniques exist to accomplish this task, including Kalman and Wiener filtering, least-mean-square (LMS) algorithms, and the Levenberg-Marquardt(L-M) algorithm. These techniques require an analytic form of the gradient of the function of the parameters to be estimated. A key feature of the simultaneous perturbation stochastic approximation (SPSA) method is that it is a gradient-free optimization technique (Spall; 1992,1998a,b, 1999). In the current problem, the function of parameters to be identified is highly non-linear and of sufficient difficulty that obtaining an analytic form of the gradient is impractical. Therefore, in this paper the

performance of the SPSA algorithm will be examined in terms of parameter selection, data requirements, and convergence performance on this non-linear problem. Results will be reported on both a first-order "standard" implementation of SPSA and on a second-order version of SPSA that tends to enhance convergence.  相似文献   
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