Measurement Error in Psychological Research: Lessons From 26 Research Scenarios

technical principles to concrete research problems that appear in a wide variety of forms and with a myriad of obscuring features, details, and idiosyncracies. This article is based on a different approach: examination of a series of concrete research scenarios that we have encountered in our work as researchers, advisors to researchers, or reviewers. This article examines 26 real-world "case studies" and explicates them on the basis of the principles of reliability theory found in Cronbach (1947, 1951) and Cronbach et al. (1972). Although we cite and rely on these sources, other sources (e.g., Thorndike, 1951) would yield identical resolutions; only the terminology would be sometimes (slightly) different. In classical measurement theory, the fundamental general formula for the observed correlation between any two measures, x and y, is yields the dissattenuation formula: