Controlling for individual heterogeneity in longitudinal models, with applications to student achievement

Longitudinal data tracking repeated measurements on individuals are highly valued for research because they offer controls for unmeasured individual heterogeneity that might otherwise bias results. Random effects or mixed models approaches, which treat individual heterogeneity as part of the model error term and use generalized least squares to estimate model parameters, are often criticized because correlation between unobserved individual effects and other model variables can lead to biased and inconsistent parameter estimates. Starting with an examination of the relationship between random effects and fixed effects estimators in the standard unobserved effects model, this article demonstrates through analysis and simulation that the mixed model approach has a ``bias compression'' property under a general model for individual heterogeneity that can mitigate bias due to uncontrolled differences among individuals. The general model is motivated by the complexities of longitudinal student achievement measures, but the results have broad applicability to longitudinal modeling.Comment: Published at http://dx.doi.org/10.1214/07-EJS057 in the Electronic Journal of Statistics (http://www.i-journals.org/ejs/) by the Institute of Mathematical Statistics (http://www.imstat.org

Violence and Violence Prevention Among African American Middle School Children

This study contributes to school-based violence prevention programs by describing typical violent interactions. The findings come from the content analysis of transcribed interviews with 58 African-American middle school students who reported their participation in 121 violent incidents. The most frequent opening moves were offensive touching, interfering with possessions, hurtful play (including teasing), backbiting, requests to do something, and insults. About half the incidents occurred in school and a quarter took place at home. Respondents who acted violently often interpreted the situation as one in which they were being attacked or threatened. Other interpretations were that antagonists thought they had done something wrong, or that antagonists were engaged in offensive behavior. In about half the incidents, violent respondents stated that the goal of their violence was retribution, and in a quarter, compliance. Most of those interviewed accepted responsibility for deliberately deciding to be violent. They justified their actions by saying they were acting rationally by retaliating for harmful behavior done to them, punishing others for offensive behavior, or defending themselves, their friends, or their relatives. Incidents often escalated as older family members joined the transaction. Nonviolent responses were discouraged by the bad public image they presented. The paper lists recommendations for school-based conflict resolution that follow from these research findings

Catastrophic crisis communication: a study of hospital crisis planning following the September 11, 2001 terrorist attacks

The purpose of this study was to determine whether hospitals in southern New Jersey and throughout the United States were prepared to respond to catastrophic crisis situations and find out if hospitals have changed or improved crisis plans since the September 11, 2001 terrorist attacks. To examine preparedness and improvement of crisis plans since September 11, 2001, the researcher employed qualitative and quantitative studies. The researcher conducted in-depth personal interviews with public relations specialists from four southern New Jersey hospitals and sent email surveys to 40 hospitals throughout the United States to find out if these facilities felt prepared to respond to catastrophic crises and see if their crisis plans have been changed or improved since September 11, 2001. Findings of the study indicate that hospitals in southern New Jersey and throughout the United States do feel prepared to respond to catastrophic crisis. In addition, many hospitals update crisis plans on a regular basis

Missing data in value-added modeling of teacher effects

The increasing availability of longitudinal student achievement data has heightened interest among researchers, educators and policy makers in using these data to evaluate educational inputs, as well as for school and possibly teacher accountability. Researchers have developed elaborate "value-added models" of these longitudinal data to estimate the effects of educational inputs (e.g., teachers or schools) on student achievement while using prior achievement to adjust for nonrandom assignment of students to schools and classes. A challenge to such modeling efforts is the extensive numbers of students with incomplete records and the tendency for those students to be lower achieving. These conditions create the potential for results to be sensitive to violations of the assumption that data are missing at random, which is commonly used when estimating model parameters. The current study extends recent value-added modeling approaches for longitudinal student achievement data Lockwood et al. [J. Educ. Behav. Statist. 32 (2007) 125--150] to allow data to be missing not at random via random effects selection and pattern mixture models, and applies those methods to data from a large urban school district to estimate effects of elementary school mathematics teachers. We find that allowing the data to be missing not at random has little impact on estimated teacher effects. The robustness of estimated teacher effects to the missing data assumptions appears to result from both the relatively small impact of model specification on estimated student effects compared with the large variability in teacher effects and the downweighting of scores from students with incomplete data.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS405 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Flexibility and efficiency in university soil science education: The Oz Soils 3.0 CD-ROM

Based on a 1997 CUTSD grant, we have developed 18 teaching modules for a CD-ROM based interactive multimedia program, called Oz Soils, which is integrated into the teaching curriculum of internal and external undergraduate units at The University of New England to assist students in understanding the fundamental concepts and processes of soil science. Oz Soils incorporates a flexible self-directed learning structure to help achieve this understanding. Other unit resources include a study guide, a practical workbook, and on-line quiz modules conducted through WebCT. Oz Soils makes use of interactive animations, still graphics, and text, and includes interactive selfassessment questions. The program can be readily integrated into a range of study areas which require a basic understanding of soil science including agriculture, forestry, ecosystems management, natural resources, ecology, engineering, mine site rehabilitation, geology, geography and biology. Oz Soils has been extremely well received by students and has been adopted by many Australian university departments which require teaching aspects of soil science. A brief rationale for developing the Oz Soils resource is presented, together with some outcomes of student questionnaires and research on a learning strategies study

Cultural identity and social capital in Italy

Italy became one nation only relatively recently and as such there remains significant regional variation in trust in government and society (so-called “social capital”) as well as in language and diet. In an experiment conducted across three Italian cities we exploit variation in family background generated through internal migration and make use of novel measures of social capital, language and diet to develop a new index of cultural heritage. Our new index predicts social capital, while self-reported identity does not. The missing link between the past and current identity seems to come through grandparents (especially maternal grandmothers) who have a strong role in developing the cultural identity of their grandchildren

The effects of social capital on Government performance and turnover : theory and evidence from Italian municipalities

This paper makes three contributions. First, it presents a theoretical analysis of how both the civic preference and information aspects of social capital impact on government performance and turnover, employing a political agency model with both moral hazard and adverse selection. Second, it presents novel measures of both local government performance and on social capital at the Italian municipality level, using administrative data and an online survey respectively. Third, empirical results show that higher social capital improves government performance, especially in the first term of office, but also increases turnover of incumbent mayors, as predicted by the theory. The voting rule predicted by the theory has the feature that the level effect of social capital on the incumbent vote share is negative, but the interaction between social capital and performance is positive. Our empirical results also support this prediction