The Programme for International Student Assessment (PISA) introduced creative thinking as an innovative domain in 2022. This paper examines the unique methodological issues in international assessments and the implications of measuring creative thinking within PISA's framework, including stratified sampling, rotated form designs, and a distinct…

This article highlights the problem of omitted variable bias in research on the causal effect of financial aid on college-going. I first describe the problem of self-selection and the resulting bias from omitted variables. I then assess and explore the strengths and weaknesses of random assignment, multivariate regression, proxy variables, fixed…

A practical theory is offered for probing external validity, the generalization of causal relationships. This alternative theory is built around five principles abstracted from research on construct validation. It emphasizes purposive sampling for theoretical ends rather than random sampling to represent a population. (SLD)

Studies evaluating hypotheses about sources of differential item functioning (DIF) are classified into two categories: observational studies evaluating operational items and randomized DIF studies evaluating specially constructed items. For observational studies, advice is given for item classification, sample selection, the matching criterion,…