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941.
Does childhood family structure help create stratification in adult education and labor market attainment?: An argument for the selectivity perspective 下载免费PDF全文
Stratification in opportunities for and attainment of educational credentials, stable and well‐paying jobs, wealth, and socioeconomic status causes problems for both individuals and the societies they live in. It is unclear, however, the extent to which important childhood experiences, such as family structure and transitions, shapes opportunity paths and eventual attainment later in adulthood. The intergenerational transmission literature suggests little if any role of family structure in later attainment, while family scholars and demographers find more compelling evidence that childhood family structures and transitions are influential in adulthood. We argue that both perspectives may be identifying selectivity processes that help explain potential links between families of origin and differences in opportunities to attain education, careers, and status. We then provide suggestions for future work in each of these scholarly traditions to help untangle both the degree to which family structure does or does not affect adult attainment and whether selectivity is the key explanation for any such relationships. 相似文献
942.
Objectives: The authors conducted an initial validation of the Arizona Sexual Experience Scale (ASEX) and examined the sexual function of Spanish and Portuguese young adults. Methods: Participants were 523 Spanish and 595 Portuguese heterosexual young adults who completed a background questionnaire, the ASEX, and measures of sexual sensation seeking, excitation, and inhibition. Results: The ASEX showed good reliability and validity. Participants reported good sexual function. The most prevalent difficulties in men were related to desire and orgasm, and to orgasm and satisfaction in women. Conclusions: This is a psychometrically sound instrument to assess sexual functioning in Spanish and Portuguese young adults. 相似文献
943.
In most of the existing specialized literature, monitoring regression models are a special case of profile monitoring. However, not every regression model always represents appropriately a profile data structure. This is clearly the case of the Weibull regression model (WRM) with common shape parameter γ. Even though it might be thought that existing methodologies (especially likelihood-ratio (LRT)-based methods) for monitoring generalized linear profiles can also be successfully applied to monitoring regression models with time-to-event response, it will be shown in this paper that those methodologies work fairly acceptable just for data structures with 1000 observations at least approximately. It was found out that some corrections, often referred to as Bartlett's adjustments, are needed to be implemented in order to improve the accuracy of using the asymptotic distributional properties of the LRT statistic for carrying out the monitoring of WRM with relatively small and moderate dimensions of the available datasets. Simulation studies suggest that the use of the aforementioned corrections make the resulting charts work quite acceptable when available data structures contain 30 observations at least. Detection abilities of the proposed schemes improve as dataset dimension increases. 相似文献
944.
J. A. Roldán-Nofuentes R. M. Amro 《Journal of Statistical Computation and Simulation》2017,87(3):530-545
Case–control design to assess the accuracy of a binary diagnostic test (BDT) is very frequent in clinical practice. This design consists of applying the diagnostic test to all of the individuals in a sample of those who have the disease and in another sample of those who do not have the disease. The sensitivity of the diagnostic test is estimated from the case sample and the specificity is estimated from the control sample. Another parameter which is used to assess the performance of a BDT is the weighted kappa coefficient. The weighted kappa coefficient depends on the sensitivity and specificity of the diagnostic test, on the disease prevalence and on the weighting index. In this article, confidence intervals are studied for the weighted kappa coefficient subject to a case–control design and a method is proposed to calculate the sample sizes to estimate this parameter. The results obtained were applied to a real example. 相似文献
945.
We study objective Bayesian inference for linear regression models with residual errors distributed according to the class of two-piece scale mixtures of normal distributions. These models allow for capturing departures from the usual assumption of normality of the errors in terms of heavy tails, asymmetry, and certain types of heteroscedasticity. We propose a general non-informative, scale-invariant, prior structure and provide sufficient conditions for the propriety of the posterior distribution of the model parameters, which cover cases when the response variables are censored. These results allow us to apply the proposed models in the context of survival analysis. This paper represents an extension to the Bayesian framework of the models proposed in [16]. We present a simulation study that shows good frequentist properties of the posterior credible intervals as well as point estimators associated to the proposed priors. We illustrate the performance of these models with real data in the context of survival analysis of cancer patients. 相似文献
946.
947.
In semidefinite programming (SDP), we minimize a linear objective function subject to a linear matrix being positive semidefinite. A powerful program, SeDuMi, has been developed in MATLAB to solve SDP problems. In this article, we show in detail how to formulate A-optimal and E-optimal design problems as SDP problems and solve them by SeDuMi. This technique can be used to construct approximate A-optimal and E-optimal designs for all linear and nonlinear regression models with discrete design spaces. In addition, the results on discrete design spaces provide useful guidance for finding optimal designs on any continuous design space, and a convergence result is derived. Moreover, restrictions in the designs can be easily incorporated in the SDP problems and solved by SeDuMi. Several representative examples and one MATLAB program are given. 相似文献
948.
Research has examined various elements of Twitter; however, no scholarship has explored how sociologists currently use the platform. This empirically driven paper explores how individuals that self-identify as sociologists on Twitter use the popular micro-blogging social media site. A total of 152,977 tweets from Twitter profiles of 130 sociologists were collected and examined using qualitative media analysis. The potential use of Twitter allows the sociologist to become both the generator and interlocutor of dialogue with publics. We frame our data analysis and discussion around the core theme of expertise - namely, the role that expertise plays in the use of Twitter by sociologists. Our findings indicate that when sociologists used Twitter as sociologists (i.e., drawing upon their stated research expertise) little direct engagement with publics occurred. Thus, while sociologists appear to be using Twitter as a space for public sociology, the use of this interactive platform is mostly limited to the generation of content, a finding consistent with Burawoy’s traditional form of public sociology. Suggestions for future research are noted. 相似文献
949.
Fathers' roles in family life have changed dramatically over the past 50 years. In addition to ongoing breadwinning responsibilities, many fathers are now involved in direct caregiving and engagement with children. Yet there is considerable variation in what fathers do, especially depending on whether they live with or away from their child. In this article, the authors use data from the Fragile Families and Child Wellbeing Study (N = 3,869) to describe how fathers' economic capacities (money) and direct involvement with children (time) are associated over child ages 1 to 9 for resident versus nonresident fathers, net of confounding factors. They found suggestive evidence that money and time investments operate differently across residential contexts: Resident fathers experience a trade‐off between market work and time involved with children. In contrast, nonresident fathers' higher economic capacities are associated with more time involvement, underscoring the greater challenge for such fathers to remain actively involved. 相似文献
950.
Using data from the Fragile Families and Child Wellbeing survey linked to respondents' medical records (N = 2,870), this study examines the association between grandparents' education and birth outcomes and explores potential pathways underlying this relationship. Results show that having a grandfather with less than a high school education was associated with a 93 gram reduction in birth weight, a 59% increase in the odds of low birth weight, and a 136% increase in the odds of a neonatal health condition when compared with having a grandfather with a high school education or more. These associations were partially accounted for by mother's educational attainment and marital status as well as by prenatal history of depression, hypertension, and prenatal health behaviors, depending on the specific outcome. The findings from this study call for heightened attention to the multigenerational influences of educational attainment for infant health. 相似文献