Methods | Statistics | Clinical | Educational | Industrial |
Professional items | World psychology | Reliability does not
imply validity. That is, a reliable measure is measuring
something consistently, but not necessarily what it is supposed
to be measuring. For example, while there are many reliable
tests of specific abilities, not all of them would be valid for
predicting, say, job performance. In terms of accuracy and
precision, reliability is precision, while validity is accuracy.
Reliability may be estimated through a variety of methods that
fall into two types: single-administration and multiple-
administration. Multiple-administration methods require that two
assessments are administered. - Test-retest reliability, is
estimated as the Pearson product-moment correlation coefficient
between two administrations of the same measure. This is
sometimes known as the coefficient of stability - Alternate
forms reliability is estimated by the Pearson product-moment
correlation coefficient of two different forms