Test reliability (consistency) is an essential requirement for
test validity. Test validity is the degree to which a test
measures what it is designed to measure. Researchers use four
methods to check the reliability of a test: the test-retest
method, alternate forms, internal consistency, and inter-scorer
reliability. Not all of these methods are used for all tests.
Each method provides research evidence that the responses are
consistent under certain circumstances. There are four distinct
types of reliability. (1.) Test-Retest- a method of estimating
test reliability in which a test developer or researcher gives
the same test to the same group of research participants on two
different occasions. The results from the two tests are then
correlated to produce a stability coefficient. Studying the
coefficients for a particular test allows the assessor to see
how stable the test is over time. Example: The information
obtained for test-retest reliability of the WISC-IV was
evaluated with information from 243 chil