Proficiency with written communication (WC) is critical for success in college and careers. As a result, institutions face a growing challenge to accurately evaluate their students' writing skills to obtain data that can support demands of accreditation, accountability, or curricular improvement. Many current standardized measures, however, lack…

This manual contains information about the American College Test (ACT) Plan® program. The principal focus of this manual is to document the Plan program's technical adequacy in light of its intended purposes. This manual supersedes the 2011 edition. The content of this manual responds to requirements of the testing industry as established in the…

ACT college test publisher provided scores. On average, non-homeschoolers performed better than homeschoolers, by about two items, out of sixty items, on the ACT mathematics test that was analyzed. This result may be due to the different teaching/learning media used in teaching each of the two groups, to different teacher/student interaction, or…

The stability of selected indices for detecting differential item performance (item bias), from one randomly equivalent sample to another, is addressed. Some recent research has criticized these indices as too unreliable for utility in measuring bias in achievement test items. Using data from a national testing of the ACT Assessment, however, this…

This report builds on and extends existent research on population invariance to new tests and issues. The authors lay the foundation for a deeper understanding of the use of population invariance measures in a wide variety of practical contexts. The invariance of linear, equipercentile and IRT equating methods are examined using data from five…