Terrorism elicits strong public reactions immediately after the attack, with important implications for democratic institutions and individual well-being. Are these effects short-lived? We answer this question using a natural experiment design and combining data on terrorist attacks in the United Kingdom with a Continuous Monitoring Survey. We find that heightened risk perceptions and emotional reactions in the wake of deadly attacks do not dissipate in the very short run but are sustained over time and up to 120 days after the attacks. Whereas large-scale attacks cause a long-lasting shift in risk assessments and emotions, the corresponding effect of smaller-scale terrorism incidents appears to subside within one month. Overall, the impact of terrorism does not fade away easily.

The majority of research papers in computer-assisted language learning (CALL) report on primarily quantitative studies measuring the effectiveness of pedagogical interventions in relation to language learning outcomes. These studies are frequently referred to in the literature as experiments, although this designation is often incorrect because of the approach to sampling that has been used. This methodological discussion paper provides a broad overview of the current CALL literature, examining reported trends in the field that relate to experimental research and the recommendations made for improving practice. It finds that little attention is given to sampling, even in review articles. This indicates that sampling problems are widespread and that there may be limited awareness of the role of formal sampling procedures in experimental reasoning. The paper then reviews the roles of two key aspects of sampling in experiments: random selection of participants and random assignation of participants to control and experimental conditions. The corresponding differences between experimental and quasi-experimental studies are discussed, along with the implications for interpreting a study’s results. Acknowledging that genuine experimental sampling procedures will not be possible for many CALL researchers, the final section of the paper presents practical recommendations for improved design, reporting, review, and interpretation of quasi-experimental studies in the field.

Quasi-experimental techniques were developed to provide decision-making tools for documenting the impacts of developmental highways in rural areas. Regression discontinuity analysis (RDA) with limited observations was used to compare economic changes in highway counties to those in adjacent and non-adjacent control counties. The RDA models found statistically significant changes in population, per capita income, and taxable sales related to highway development. The study found that some counties benefitted from developmental highways, some were unchanged, while some experienced economic decline. RDA models with adjacent controls had better explanatory powers while those with non-adjacent controls were more sensitive to highway-related changes in economic activity. When significant non-highway activities were present, adjacent control models may have understated highway-related impacts, while non-adjacent control models may have overstated these impacts. Arguments for using adjacent and non-adjacent experimental designs are discussed.

The Missouri Mothers and Their Children Study (MO-MATCH) was specifically designed to critically investigate prenatal environmental influences on child attention problems and associated learning and cognitive deficits. The project began as a pilot study in 2004 and was formally launched in 2008. Participants in the study were initially identified via the Department of Vital Statistics birth record (BR) database. Interview and lab-based data were obtained from: (1) mothers of Missouri-born children (born 1998–2005), who smoked during one pregnancy but not during another pregnancy; (2) biological fathers when available; and (3) the children (i.e., full sibling pairs discordant for exposure to maternal smoking during pregnancy (SDP). This within-mother, between-pregnancy contrast provides the best possible methodological control for many stable maternal and familial confounding factors (e.g., heritable and socio-demographic characteristics of the mother that predict increased probability of SDP). It also controls for differences between mothers who do and do not smoke during pregnancy, and their partners, that might otherwise artifactually create, or alternatively mask, associations between SDP and child outcomes. Such a design will therefore provide opportunities to determine less biased effect sizes while also allowing us to investigate (on a preliminary basis) the possible contribution of paternal or other second-hand smoke exposure during the pre, peri, and postnatal periods to offspring outcome. This protocol has developed a cohort that can be followed longitudinally through periods typically associated with increased externalizing symptoms and substance used initiation.