This article develops new closed-form variance expressions for power analyses for commonly used difference-in-differences (DID) and comparative interrupted time series (CITS) panel data estimators. The main contribution is to incorporate variation in treatment timing into the analysis. The power formulas also account for other key design features…

Educators and researchers strive to build policies and practices on data and evidence, especially on academic achievement scores. When assessment scores are inaccurate for specific student populations or when scores are inappropriately used, even data-driven decisions will be misinformed. To maximize the impact of the research-practice-policy…

This supplement concerns Appendix E of the "What Works Clearinghouse (WWC) Procedures Handbook, Version 4.1." The supplement extends the range of designs and analyses that can generate effect size and standard error estimates for the WWC. This supplement presents several new standard error formulas for cluster-level assignment studies,…

The use of multilevel modeling (MLM) to analyze nested data has grown in popularity over the years in the study of school psychology. However, with the increase in use, several statistical misconceptions about the technique have also proliferated. We discuss some commonly cited myths and golden rules related to the use of MLM, explain their…

There are situations within middle school settings where measurements of students and teachers are used for high-stakes decisions. For example, student performance is used as an indicator of teacher quality or determines student eligibility for particular types of support services. Given the high-stakes nature of these types of assessments,…

Covariate adjustment can increase the precision of estimates by removing unexplained variance from the error in randomized experiments, although chance covariate imbalance tends to counteract the improvement in precision. The author develops an easy measure to examine chance covariate imbalance in randomization by standardizing the average…

This manual has been produced to familiarize data users with the design, and the procedures followed for data collection and processing, in the base year and first follow-up of the High School Longitudinal Study of 2009 (HSLS:09), with emphasis on the first follow-up. It also provides the necessary documentation for use of the public-use data…

The manual that accompanies these appendices was produced to familiarize data users with the design, and the procedures followed for data collection and processing, in the base year and first follow-up of the High School Longitudinal Study of 2009 (HSLS:09), with emphasis on the first follow-up. It also provides the necessary documentation for use…

This methodological brief introduces the readers to the propensity score matching method, which can be used for enhancing the validity of causal inferences in research situations involving nonexperimental design or observational research, or in situations where the benefits of an experimental design are not fully realized because of reasons beyond…

This chapter summarizes ten selected issues and common problems that arise in most assessment research projects. These include: (1) the uses of grades in assessment; (2) institutional review boards; (3) research design as a compromise; (4) standardized testing; (5) self-reported measures; (6) missing data; (7) weighting data; (8) conditional…

This article reports on a delicious finding from a recent study claiming a causal link between dark chocolate consumption and blood pressure reductions. In the article, I provide ideas for using this study to whet student appetites for a discussion of statistical ideas, including experimental design, measurement error and inference methods.

The constraints of conducting evaluations in real-world settings often necessitate the implementation of less than ideal designs. Unfortunately, the standard method for estimating the precision of a result (i.e., confidence intervals [CI]) cannot be used for evaluative conclusions that are derived from multiple indicators, measures, and data…

The zeitgeist for reform in education precipitated a number of changes in assessment. Among these are performance assessments, sometimes linked to "high stakes" accountability decisions. In some instances, the trustworthiness of these decisions is based on variance components and error variances derived through generalizability theory.…

The primary purpose of this article was to offer a methodological critique in support of arguments that racial categories should be replaced as explanatory constructs in psychological research and theory. To accomplish this goal, the authors (a) summarized arguments for why racial categories should be replaced; (b) used principles of the…

The AP Course Audit utilizes a criterion-based professional judgment method of analysis within a nested multi-step review process. The overall goal of the methodology is to yield a final judgment on each syllabus that is ultimately valid. While reviewer consistency is an important consideration, the most important goal is to reach a final judgment…