The Programme for the International Assessment of Adult Competencies (PIAAC) has been planned as an ongoing program of assessment. The first cycle of the assessment has involved two "rounds." The first round, which is covered by this report, took place over the period of January 2008-October 2013. The main features of the first cycle of…

Item response theory (IRT) methodology is introduced as a tool for improving assessment instruments used with people who have disabilities. Need for this approach in rehabilitation is emphasized; differences between IRT and classical test theory are clarified. Concepts essential to understanding IRT are defined, necessary data assumptions are…

Addresses common pitfalls in homogeneous scale construction in clinical and social psychology. Offers suggestions about item writing, answer scale formats, data analysis procedures, and overall scale development strategy. Emphasizes effective use of factor-analytic methods to select items for scales and to determine its proper location in…