RAND Corporation

About: RAND Corporation is a nonprofit organization based out in Santa Monica, California, United States. It is known for research contribution in the topics: Population & Health care. The organization has 9602 authors who have published 18570 publications receiving 744658 citations.

Peer effects in private and public schools across countries

Abstract: Many argue that the composition of a school or classroom-that is, the characteristics of the students themselves-affect the educational attainment of an individual student. This influence of the students in a classroom is often referred to as a peer effect. There have been few systematic studies that empirically examine the peer effect in the educational process. In this research, we examine the peer effect with a unique data set that includes individual student achievement scores and comprehensive characteristics of the students' families, teachers, other school characteristics, and peers for five countries. The data allow an examination of peer effects in both private and public schools in all countries. Our analysis indicates that peer effects are a significant determinant of educational achievement; the effects of peers appear to be greater for low-ability students than for high-ability students. The finding is robust across countries but not robust across school type. © 2000 by the Association for Public Policy Analysis and Management.

Many objective robust decision making for complex environmental systems undergoing change

Abstract: This paper introduces many objective robust decision making (MORDM). MORDM combines concepts and methods from many objective evolutionary optimization and robust decision making (RDM), along with extensive use of interactive visual analytics, to facilitate the management of complex environmental systems. Many objective evolutionary search is used to generate alternatives for complex planning problems, enabling the discovery of the key tradeoffs among planning objectives. RDM then determines the robustness of planning alternatives to deeply uncertain future conditions and facilitates decision makers' selection of promising candidate solutions. MORDM tests each solution under the ensemble of future extreme states of the world (SOW). Interactive visual analytics are used to explore whether solutions of interest are robust to a wide range of plausible future conditions (i.e., assessment of their Pareto satisficing behavior in alternative SOW). Scenario discovery methods that use statistical data mining algorithms are then used to identify what assumptions and system conditions strongly influence the cost-effectiveness, efficiency, and reliability of the robust alternatives. The framework is demonstrated using a case study that examines a single city's water supply in the Lower Rio Grande Valley (LRGV) in Texas, USA. Results suggest that including robustness as a decision criterion can dramatically change the formulation of complex environmental management problems as well as the negotiated selection of candidate alternatives to implement. MORDM also allows decision makers to characterize the most important vulnerabilities for their systems, which should be the focus of ex post monitoring and identification of triggers for adaptive management.

What Do Test Scores in Texas Tell Us

Abstract: We examine the results on the Texas Assessment of Academic Skills (TAAS), the highest-profile state testing program and one that has recorded extraordinary recent gains in math and reading scores. To investigate whether the dramatic math and reading gains on the TAAS represent actual academic progress, we have compared these gains to score changes in Texas on another test, the National Assessment of Educational Progress (NAEP). Texas students did improve significantly more on a fourth-grade NAEP math test than their counterparts nationally. But, the size of this gain was smaller than their gains on TAAS and was not present on the eighth-grade math test. The stark differences between the stories told by NAEP and TAAS are especially striking when it comes to the gap in average scores between whites and students of color. According to the NAEP results, that gap in Texas is not only very large but increasing slightly. According to TAAS scores, the gap is much smaller and decreasing greatly. Many schools are devoting a great deal of class time to highly specific TAAS preparation. While this preparation may improve TAAS scores, it may not help students develop necessary reading and math skills. Schools with relatively large percentages of minority and poor students may be doing this more than other schools. We raise serious questions about the validity of those gains, and caution against the danger of making decisions to sanction or reward students, teachers and schools on the basis of test scores that may be inflated or misleading. Finally, we suggest some steps that states can take to increase the likelihood that their test results merit public confidence and provide a sound basis for educational policy.

The PedsQL 4.0 as a school population health measure: feasibility, reliability, and validity.

Abstract: Background: The application of health-related quality of life (HRQOL) as a school population health measure may facilitate risk assessment and resource allocation, the tracking of student health at the school and district level, the identification of health disparities among schoolchildren, and the determination of health outcomes from interventions and policy decisions at the school, district, and county level. Objective:To determine the feasibility, reliability, and validity of the 23-item PedsQLTM 4.0 (Pediatric Quality of Life InventoryTM) Generic Core Scales as a school population health measure for children and adolescents. Design: Survey conducted in 304 classes at 18 elementary schools, 4 middle schools, and 3 high schools within a large metropolitan school district. Methods:The PedsQLTM 4.0 Generic Core Scales (Physical, Emotional, Social, School Functioning) were completed by 2437 children ages 8–18 and 4227 parents of children ages 5–18. Results:The PedsQLTM 4.0 evidenced minimal missing responses, achieved excellent reliability for the Total Scale Score (α = 0.89 child, 0.92, parent report), and distinguished between healthy children and children with chronic health conditions. The PedsQLTM 4.0 was related to indicators of socioeconomic status (SES) at the school and district level. The PedsQLTM School Functioning Scale was significantly correlated with standardized achievement scores based on the Stanford 9. Conclusion: The results demonstrate the feasibility, reliability and validity of the PedsQLTM 4.0 Generic Core Scales as a school population health measure. The implications of measuring HRQOL in schoolchildren at the school, district, and county level for identifying and ameliorating health disparities are discussed.

Mercury and methylmercury, in individual zooplankton: Implications for bioaccumulation

Abstract: Using trace-metal-clean sampling and handling techniques along with ultrasensitive analytical procedures, it is possible to measure both total Hg and monomethylmercury (methyl-Hg) in natural planktonic communities with the same level of taxonomic, ontogenic, and trophic resolution that is currently possible in fish communities. In an experimentally manipulated lake, both acidification and trophic position enhanced the bioaccumulation of methyl-Hg in the plankton. A consistant pattern of methyl-Hg enrichment (2−4 ×) in water, bulk phytoplankton, and individual zooplankton was associated with a 1.5 unit pH decrease in Little Rock Lake. Regardless of pH, bioconcentration factors [Bf = log(Cb/Cw), where Cb and Cw are Hg concentrations in biota and water] were substantially higher for methyl-Hg than those for total Hg or nonmethyl-Hg at three pelagic trophic levels (~10−100×). Between each trophic level, the Bf(methyl-Hg) increased by ~0.5 log units, clearly indicating biomagnification. Although somewhat higher in the acidified basin, Bf(methyl-Hg) was more strongly influenced by trophic position than by pH. This suggests that methyl-Hg was bioaccumulated largely in proportion to supply and that acidification may have directly increased supply to the base of the food chain.