This digest discusses sources of error in testing, several approaches to estimating reliability, and several ways to increase test reliability. Reliability has been defined in different ways by different authors, but the best way to look at reliability may be the extent to which measurements resulting from a test are characteristics of those being…

Several common sources of error in assessment that depends on the use of judges are identified, and ways to reduce the impact of rating errors are examined. Numerous threats to the validity of scores based on ratings exist. These threats include: (1) the halo effect; (2) stereotyping; (3) perception differences; (4) leniency/stringency error; and…