The purpose of this paper is to highlight some psychometric cautions that should be observed when seeking to develop short form versions of tests. Several points are made: (1) score reliability is impacted directly by the characteristics of the sample and testing conditions; (2) sampling error has a direct influence on reliability and factor…

The testlet, a bundle of test items, alleviates some problems associated with computerized adaptive testing: context effects, lack of robustness, and item difficulty ordering. While testlets may be linear or hierarchical, the most useful ones are four-level hierarchical units, containing 15 items and partitioning examinees into 16 classes. (GDC)