Precision is a key facet of test development, with score reliability determined primarily according to the types of error one wants to approximate and demonstrate. This article identifies and discusses several primary forms of reliability estimation: internal consistency (i.e., split-half, KR-20, a), test-retest, alternate forms, interscorer, and…

Many educators consider grades calculated from statistical algorithms more accurate, objective, and reliable than grades they calculate themselves. But in this research, the authors first asked teachers to use their professional judgment to choose a summary grade for hypothetical students. When the researchers compared the teachers' grade with the…