Reliability refers to the consistency of scores obtained by the same persons when they are re-examined with the same test on different occasions or with different sets of equivalent items or under other variable examining conditions (Anastasi & Urbina, 1997). Reliability also refers to the measuring instrument's accuracy or precision. The property of getting the correct measurement is accuracy while the property of getting self-consistent results is precision.
All types of reliability can be expressed in terms of a correlation coefficent (r) which expresses the degree of correspondence or relationship between two sets of scores. Correlation coefficients can be computed in various ways depending on the nature of the data (Catane, 2000).
All types of reliability can be expressed in terms of a correlation coefficent (r) which expresses the degree of correspondence or relationship between two sets of scores. Correlation coefficients can be computed in various ways depending on the nature of the data (Catane, 2000).