Pub. date: 2008 | Online Pub. Date: November 27, 2007 | DOI: 10.4135/9781412953948 | Print ISBN: 9781412928168 | Online ISBN: 9781412953948| Publisher:SAGE Publications, Inc.About this encyclopedia
Researchers and practitioners rely on a variety of instruments for measurement, such as scales, surveys, and recordings. For an instrument to be useful, it must be both reliable (i.e., measurements made using it are consistent and can be replicated) and valid (i.e., it measures what the researcher thinks it is measuring). This entry discusses one aspect of reliability, interrater reliability, in the general context of reliability in measurement. Reliability essentially refers to repeatability. In asking how reliable an instrument is, we are asking whether we would get the same results if we were to take the same measurement of the same entity over and over again. Reliability does not require that an instrument deliver perfect measurements; rather, it assumes that some error occurs when we use an instrument repeatedly but that the error is random rather than systematic. As a result, after multiple measures using the same instrument, the random ...