Bounding,An Accessible Method for Estimating Principal Causal Effects,Examined and Explained

Estimating treatment effects for subgroups defined by posttreatment behavior (i.e., estimating causal effects in a principal stratification framework) can be technically challenging and heavily reliant on strong assumptions. We investigate an alternative path: using bounds to identify ranges of possible effects that are consistent with the data. This simple approach relies on fewer assumptions and yet can result in policy-relevant findings. As we show, even moderately predictive covariates can be used to substantially tighten bounds in a straightforward manner. Via simulation, we demonstrate which types of covariates are maximally beneficial. We conclude with an analysis of a multisite experimental study of Early College High Schools. When examining the program's impact on students completing the ninth grade “on-track” for college, we find little impact for ECHS students who would otherwise attend a high-quality high school, but substantial effects for those who would not. This suggests a potential benefit in expanding these programs in areas primarily served by lower quality schools.     

Predicting transition and adjustment to college: biomedical and behavioral science aspirants’ and minority students’ first year of college

The purpose of this study is to explore key factors that impact the college transition of aspiring underrepresented minority students in the biomedical and behavioral sciences, in comparison with White, Asian students and non-science minority students. We examined successful management of the academic environment and sense of belonging during the first college year. Longitudinal data were derived from the Higher Education Research Institute’s (HERI) 2004 Cooperative Institutional Research Program (CIRP) Freshman Survey and the 2005 Your First College Year (YFCY) Survey. Using a reformulation of the integration model (Nora, Barlow, and Crisp, 2005), we find concerns about college financing, negotiating family support and responsibility, and campus racial dynamics (perceived and behavioral) affect student adjustment and sense of integration in the first year. This study was made possible by the support of the National Institute of General Medical Sciences, NIH Grant Number 1 RO1 GMO71968-01. This independent research and the views expressed here do not indicate endorsement by the sponsor.     

The Relationship between Attitudes, Knowledge, and Demographic Variables of High School Teachers Regarding Food Irradiation

ABSTRACT:  The purpose of this study was to use a validated instrument to determine the attitudes and knowledge of high school teachers regarding food irradiation, and to determine the correlations among their knowledge and attitudes and certain demographic variables. Knowledge and attitudes about food irradiation were measured in selected high school family and consumer sciences teachers ( n = 121) who taught Food and Nutrition, Food Science and Technology, and/or Food Production Management and Services, via a 24-item instrument with 6 factors. Results revealed these teachers held neutral to positive attitudes about the safety of irradiated foods, their perception of the risk of foodborne illness, and learning about food irradiation, and neutral to negative perceptions of their understanding of food irradiation and their competence to teach about it. These teachers had a moderate knowledge base regarding food irradiation. Teachers' attitudes regarding the safety of food irradiation were positively correlated with their perceived understanding of food irradiation, actual knowledge of it, and competence to teach about it. Their perceived understanding of food irradiation was positively correlated with competence to teach about it, knowledge, and attitudes toward the safety of food irradiation. The only demographic variable correlated with knowledge or attitudes was teachers' previous food irradiation educational experiences. These data suggest the importance of education for family and consumer sciences teachers concerning food irradiation.     

Fear-motivated vicious-circle behavior maintained through secondary punishment

Two experiments attempted to establish vicious-circle behavior through fear motivation combined with secondary punishment. In Experiment 1, rats were trained with two CSs, a tone and a buzzer, paired with shock in different contexts. Secondary punishment based on delay and trace conditioning procedures facilitated running in fear-motivated rats, relative to four control groups. In Experiment 2, rats were given pairings of a tone CS with shock, and a buzzer CS with a drop into a water tank. Fear-motivated rats which received secondary punishment during either 33% or 100% of test trials exhibited self-punitive running relative to a nonpunished (0%) group and a backward-conditioning control group. Results indicate that “all secondary” vicious-circle behavior can be established through Pavlovian conditioning, thus supporting a conditioned fear interpretation.     

Reinstatement of postresponse stimuli prior to reward in delayed-reward discrimination learning by pigeons

Delayed-reward learning in pigeons was examined using a simultaneous red-green visual discrimination task in which the conditions during the delay interval were varied between groups. The nondifferential group received training in which the stimulus present during the 1-min delay was the same following a peck on the correct and incorrect colors. The other three groups received 1-min delay training in which different stimuli occurred in the delay interval following correct and incorrect choices. The differential group received continuous, differential stimuli during the delay. The reinstatement group received the differential stimuli in the 10 sec immediately following the choice and during the last 10 sec of the delay. The reversedcue group was treated in the same way, except that the 10-sec delay stimulus immediately following an incorrect response was also presented for 10 sec prior to reward on correct choices, and the stimulus following a correct response also occurred 10 sec before nonreward on incorrect choices. Nondifferential birds failed to learn the discrimination, while differential and reinstatement birds learned it readily. The reversed-cue birds learned to choose the incorrect stimulus. Differential and reinstatement birds showed no decrement in performance when the delay was increased to 2 min. These findings suggest that similarity of prereward and postresponse delay stimuli controls choice responding in long-delay learning, a finding compatible with both memorial and conditioned reinforcement interpretations.     

Matching Cloze as an Evaluation Procedure for Slow Learning Children

The matching cloze procedure, which does not require language production skills and which is simple enough for the classroom teacher to construct unaided, was originally developed to measure reading skills of elementary English‐second‐language pupils. The results of this pilot study with opportunity school children indicate the validity of the procedure as an evaluation technique for slow learning children.