Methods of Estimating Reliability
In determining reliability, it would be desirable to obtain two sets of measures under identical conditions and then compare the results. This procedure is impossible, of course, because the conditions under which assessment data are obtained can never be identical. As a substitute for this ideal procedure, several methods of estimating reliability have been introduced.
- American Educational Research Association, American Psychological Association, & National Council on Measurement in Education, 1999
Method |
Type of MeasureMeasure of stability
Measure of equivalence Measure of stability and equivalence Measure of internal consistency Measure of internal consistency Measure of consistency of ratings |
ProcedureGive the same test twice to the same group with some time interval between tests, from several minutes to several years
Give two forms of the test to the same group in close succession Give two forms of the test to the same group with an increased time interval between forms Give test once; score two equivalent halves of the test; correct correlation between halves to fit whole test by Spearman-Brown formula Give test once; score total test and apply Kuder-Richardson formula Give a set of student responses requiring judgmental scoring to two or more raters and have them independently score the responses |