Omitted variable bias occurs in most statistical models. Whenever a confounding variable that is correlated with both dependent and independent variables is omitted from a statistical model, estimated effects of included variables are likely to be biased due to omitted variables. This issue is particularly problematic in physics education research…

This paper examines sources of potential bias in systematic reviews and meta-analyses which can distort their findings, leading to problems with interpretation and application by practitioners and policymakers. It follows from an article that was published in the "Canadian Journal of Communication" in 1990, "Integrating Research…

Bias due to attrition of respondents poses a threat to the internal and external validity of research findings. Discusses methods of detecting attrition bias in longitudinal family research, and presents Heckman's procedure to correct attrition bias. Data from the University of California Longitudinal Study of Generations are used to illustrate…

Describes a class demonstration of observer bias in which students were led to believe what the research data would indicate. Reports that students reported trends consistent with the expectancy. Asserts that the demonstration had a strong and memorable effect on students and has value for demonstrating observer bias. (CFR)

Most of the recent literature on the achievement effects of school size has examined school and district performance. These studies have demonstrated substantial benefits of smaller school and district size in impoverished settings. To date, however, no work has adequately examined the relationship of size and socioeconomic status (SES) with…

Asserts that traditional approaches to multivariate analysis, including standard linear regression techniques, ignore the special character of count data. Explicates three suitable alternatives to standard regression techniques, a simple Poisson regression, a modified Poisson regression, and a negative binomial model. (MJP)

Critically reviews the influential study "Malnutrition and Environmental Enrichment" by Winick et al. (1975) and highlights what are considered to be statistical flaws in its analysis. Data in the classic study of height, weight, and IQ changes in three groups of adopted, malnourished Korean girls are reanalysed and conclusions…

This paper evaluates the logic underlying various criticisms of statistical significance testing and makes specific recommendations for scientific and editorial practice that might better increase the knowledge base. Reliance on the traditional hypothesis testing model has led to a major bias against nonsignificant results and to misinterpretation…

The findings of the Cost, Quality, and Child Outcomes (CQO) study in Child Care Centers, the largest and most visible child care research conducted in the 1990s, were widely publicized and used to promote increased spending on initiatives to improve child care quality, the redesign of subsidy systems to provide quality incentives, more stringent…