Educational assessment is used throughout the world for a range of different formative and summative purposes. Wherever an assessment is developed, whether by a teacher creating a quiz for their class, or by a testing company creating a high stakes assessment, it is necessary to decide how long the test should be. Specifically, how many questions…

The power of the procedure of W. Stout to detect deviations from essential unidimensionality in two-dimensional data was investigated for minor, moderate, and large deviations from unidimensionality using criteria for deviations from unidimensionality based on prior research. Test lengths of 20 and 40 items and sample sizes of 700 and 1,500 were…

Computer simulations were run to measure the relationship between testlet validity and factors of item pool size and testlet length for both adaptive and linearly constructed testlets. Making a testlet adaptive yields only modest increases in aggregate validity because of the peakedness of the typical proficiency distribution. (Author/SLD)

Three sections of the Graduate Record Examinations (GRE) Aptitude Test were reviewed before the introduction of the restructured test in October, 1977: research on (1) the GRE-Verbal section; (2) the GRE-Quantitative section; and (3) a planned third section, measuring analytical thinking skills. Research in all three areas focused on test…