Understanding Heterogeneity in the Impact of Public Preschool Programs

We examine the North Carolina Pre-K (NC Pre-K) program to test the hypothesis that observed variation in effects resulting from exposure to the program can be attributed to interactions with other environmental factors that occur before, during, or after the pre-k year. We examine student outcomes in 5th grade and test interaction effects between NC's level of investment in public pre-k and moderating factors. Our main sample includes the population of children born in North Carolina between 1987 and 2005 who later attended a public school in that state, had valid achievement data in 5th grade, and could be matched by administrative record review (n = 1,207,576; 58% White non-Hispanic, 29% Black non-Hispanic, 7% Hispanic, 6% multiracial and Other race/ethnicity). Analyses were based on a natural experiment leveraging variation in county-level funding for NC Pre-K across NC counties during each of the years the state scaled up the program. Exposure to NC Pre-K funding was defined as the per-4-year-old-child state allocation of funds to a county in a year. Regression models included child-level and county-level covariates and county and year fixed effects. Estimates indicate that a child's exposure to higher NC Pre-K funding was positively associated with that child's academic achievement 6 years later. We found no effect on special education placement or grade retention. NC Pre-K funding effects on achievement were positive for all subgroups tested, and statistically significant for most. However, they were larger for children exposed to more disadvantaged environments either before or after the pre-k experience, consistent with a compensatory model where pre-k provides a buffer against the adverse effects of prior negative environmental experiences and protection against the effects of future adverse experiences. In addition, the effect of NC Pre-K funding on achievement remained positive across most environments, supporting an additive effects model. In contrast, few findings supported a dynamic complementarity model. Instrumental variables analyses incorporating a child's NC Pre-K enrollment status indicate that program attendance increased average 5th grade achievement by approximately 20% of a standard deviation, and impacts were largest for children who were Hispanic or whose mothers had less than a high school education. Implications for the future of pre-k scale-up and developmental theory are discussed.     

Why I do not believe in the cost-disease

Journal of Cultural Economics -     

Effective inclusive education: Equipping education professionals with necessary skills and knowledge

As a result of educational reforms, students with disabilities are educated in inclusive settings to a greater degree than ever before. Regrettably, many teachers report that they feel unprepared to work effectively with these students. Because teacher effectiveness is strongly linked to student outcomes, these perceptions of inadequacy are clearly problematic. Improved teacher preparation is a necessity. Yet, teacher educators face their own challenges when trying to keep up with current literature and a rapidly expanding knowledge base. Web-based technology offers solutions to some of these challenges, yet not all Web-based resources are valid or reliable. The IRIS Center for Training Enhancements, funded by the U.S. Department of Education, provides free online resources for those working with struggling learners and students with disabilities. The resources are developed in collaboration with leading educational researchers, are highly rated, and are heavily used in multiple countries to improve the quality of teacher education.     

Three dimensional passivated-electrode insulator-based dielectrophoresis

In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D πDEP) is presented. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D πDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 μm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D πDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 μl/h and 70% at flow rates as high as 750 μl/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape.     

The Role of Mediators in the Development of Longitudinal Mathematics Achievement Associations

Despite research demonstrating a strong association between early and later mathematics achievement, few studies have investigated mediators of this association. Using longitudinal data (n = 1,362), this study tested the extent to which mathematics self‐concepts, school placement, executive functioning, and proficiency in fractions and division account for the association between mathematics achievement in first grade and at age 15. As hypothesized, a strong longitudinal association between first‐grade and adolescent mathematics achievement was present (β = .36) even after controlling for a host of background characteristics, including cognitive skills and reading ability. The mediators accounted for 39% of this association, with mathematics self‐concept, gifted and talented placement, and knowledge of fractions and division serving as significant mediators.     

信息安全的经济学(之二)

信息安全的经济学近来已经成为一门蓬勃发展的学科。由于分布式系统通常是由那些属于不同利益主体的计算机构成,我们发现在实现可靠性的过程中,激励机制变得和纯技术设计一样重要。这一学科领域不仅为那些传统的安全课题提供了洞见,而且还为更宽泛的领域中的研究难题拓展了思路,诸如:P2P系统设计,程序员和测试员的最优比例,隐私为何不断被侵蚀,以及数字版权管理等问题。本刊上期和本期推荐剑桥大学计算机实验室的Ross Anderson和Tyler Moore在2006年10月27日的《科学》杂志上刊发的《信息安全的经济学(The Economics of Information Security)》一文,介绍这一学科的研究和发展,以资借鉴。     

Why women succeed,and fail,in the arts

I examine and test hypotheses for the differential performance of men and women in the arts. I consider whether observed outcomes are best accounted for by differing innate and genetic endowments across the sexes, variations in training opportunities, maternal responsibilities, or discrimination in the marketplace. More generally, I also consider how social mechanisms can give rise to observed patterns of unequal achievement.     

Teachers' Responses to the Ecosystemic Approach to Changing Chronic Problem Behaviour in Schools

This paper discusses the responses of a group of thirty-three primary and two secondary teachers to a series of sessions in which the ecosystemic approach to changing chronic problem behaviour in schools was explained and then tried out in practice. Three case examples are presented, as well as related discussions, which illustrate the approach. This study follows on from the work reported in Pastoral Care , December 1998.