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21.
The equality of ordinary least squares estimator (OLSE), best linear unbiased estimator (BLUE) and best linear unbiased predictor (BLUP) in the general linear model with new observations is investigated through matrix rank method, some new necessary and sufficient conditions are given. 相似文献
22.
In this article we study the problem of classification of three-level multivariate data, where multiple q-variate observations are measured on u-sites and over p-time points, under the assumption of multivariate normality. The new classification rules with certain structured and unstructured mean vectors and covariance structures are very efficient in small sample scenario, when the number of observations is not adequate to estimate the unknown variance–covariance matrix. These classification rules successfully model the correlation structure on successive repeated measurements over time. Computation algorithms for maximum likelihood estimates of the unknown population parameters are presented. Simulation results show that the introduction of sites in the classification rules improves their performance over the existing classification rules without the sites. 相似文献
23.
Continuous non-Gaussian stationary processes of the OU-type are becoming increasingly popular given their flexibility in modelling stylized features of financial series such as asymmetry, heavy tails and jumps. The use of non-Gaussian marginal distributions makes likelihood analysis of these processes unfeasible for virtually all cases of interest. This paper exploits the self-decomposability of the marginal laws of OU processes to provide explicit expressions of the characteristic function which can be applied to several models as well as to develop efficient estimation techniques based on the empirical characteristic function. Extensions to OU-based stochastic volatility models are provided. 相似文献
24.
25.
Thomas M. Philip Danny C. Martinez Eduardo Lopez Antero Garcia 《Race Ethnicity and Education》2016,19(1):182-199
Based on a two-year self-study by a group of early-career scholars of color, we explore and purposefully name our role, within the contemporary context of neoliberal reform, as educational researchers of color who are former K-12 teachers. We capture the insights that emerged from our self-study through a close reading of dominant neoliberal educational reform discourses, particularly through an examination of the writings of Michelle Rhee and Wendy Kopp. Along three dimensions of: (1) experience as teachers; (2) solidarity with teachers; and (3) analyses of racism in schooling, we characterize prominent discourses through which educators, researchers, and the public describe teachers and teaching. We name these discursive frames to make explicit the assumptions that are embedded in each and the intentional or inadvertent consequences of each. Finally, we propose a teacher solidarity lens through which we strive to approach our research and work with teachers. 相似文献
26.
Saving behaviour and earnings uncertainty: Evidence from the British Household Panel Survey 总被引:1,自引:0,他引:1
Alessandra Guariglia 《Journal of population economics》2001,14(4):619-634
For the first time, this paper uses a panel data set, the British Household Panel Survey, to analyse saving behaviour in
Britain. One objective is to test the precautionary saving hypothesis, according to which households save to self-insure against
uncertainty. Our results show that in accordance with this hypothesis, various measures of uncertainty based on earnings variability
have a statistically significant effect on households' saving decisions. Moreover, in accordance with the life cycle model,
households save more if they expect their financial situation to deteriorate.
Received: 15 June 1999/Accepted: 4 January 2001 相似文献
27.
This paper examines a wide variety of forms, and full histories, of family structure to test existing theories of family
influences and identify needs for new theories. The focus is on links between childhood family structure and both completed
schooling and risk of a nonmarital birth. Using a 27-year span of panel (PSID) data for U.S. children, we find that: (a) change
is stressful, (b) timing during childhood is relevant, (c) adults other than parents are important, and (d) two more recently
studied family structures (mother-with-grandparent(s) and mother-with-stepfather) do not fit the molds of existing theories.
The findings suggest that new theories should consider allocation of resources and reasons people group into family structures.
Received: 11 September 1998/Accepted: 27 March 2000 相似文献
28.
KEVIN TAN DESMOND PATTON DAVID CORDOVA JOSHUA MEISLER 《Journal of social work practice in the addictions》2018,18(2):153-167
This study assesses the association of 12th-grade student factors (e.g., grades, classroom misbehaviors) with substance use (i.e., binge drinking, cigarette smoking, marijuana) across large, medium-sized, and nonmetropolitan areas. Based on a sample of 2,189 students from the 2013 Monitoring the Future data set, logistic regression analyses showed that poor student academic and behavioral factors were associated with higher substance use after controlling for gender, race, and socioeconomic status. Interaction analyses further showed no significant differences in the influence of student factors on substance use across locales. Results suggest that prevention efforts against substance use should target student factors regardless of area of residency. 相似文献
29.
EVA NOWAKOWSKI-SIMS Katie Bullard 《Journal of social work practice in the addictions》2018,18(3):305-324
Research has found significant benefits in using exercise as an adjunct treatment for substance use. This study used a qualitative grounded theory approach to explore the role of group exercise on maintaining sobriety. Sixteen persons (13 White men and 3 White women, age M = 31.81, SD = 8.23), recruited from a substance use recovery group that meets at a gym in an urban area in the Southeast part of the United States, were individually interviewed. Data were analyzed using Charmaz’s (2006) constructivist grounded theory strategies. Central themes revealed a parallel process between the steps taken to seek sobriety and those taken to maintain sobriety. The driving forces of sobriety success in both was 12 steps and group exercise programming that included elements of mentorship, structure, accountability, and fellowship or community. This study supported the use of physical group exercise as an adjunct treatment option for substance use treatment. 相似文献
30.
The purpose of this study was to determine how the ostracism of K-12 teachers influences their commitment to their schools and commitment to the teaching profession. The investment model was used to situate ostracism as a predictor of teacher commitment. Participants were 200 full-time K-12 teachers who completed a survey assessing their experiences with ostracism at work and investment model variables (i.e., investments, quality of alternatives, satisfaction, and commitment). Results confirmed investment model predictions with teachers’ investments, quality of alternatives, and satisfaction predicting their commitment to their schools and profession. Results of mediation models also demonstrated that controlling for teachers’ investments and quality of alternatives, ostracism predicted commitment indirectly through its effect on satisfaction. This study revealed that teacher commitment is explained by investment model predictions, but after controlling for those predictions, is further explained by ostracism from teacher colleagues. 相似文献