- Subject index
Measurement Theory in Action: Case Studies and Exercises comprises twenty modules, each corresponding to entire chapters in typical measurement theory texts. The modules begin with introductory concepts and a review of statistics; progress through conceptions of content, criterion-related, and construct validation, validity generalization and test-bias; and conclude with more advanced topics such as multiple regression and item response theory (IRT). Each module is composed of an overview, case studies, exercises, Internet references, and suggested further readings. An extensive glossary of key terms is also provided for quick reference. An Instructor's Resources CD containing exercises and assignments is also available.
Module 19: Item Response Theory
In Module 12, we discussed classical test theory item analysis (CTT-IA) where the focus was on how difficult and discriminating each item on a given test was within a particular sample. Under the CTT-IA framework, items on a given test are retained or discarded based on how difficult they are, as estimated by the percentage of respondents answering the item correctly—the p value—and how well they discriminate among our examinees, as estimated by an item-total correlation—the point-biserial correlation coefficient. In addition, our estimate of a person's underlying true score (or ability level) is simply the sum of the number of items correct, regardless of which items the individual answered correctly. CTT-IA has been a workhorse over the years for test ...