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Test-Retest Reliability


This method for assessing a test’s reliability involves determining the extent to which a group of people obtain similar scores on the test when it is administered at two points in time. In the case of reasoning tests, where the ability being assessed does not change substantially over time, the two occasions when the test is administered may be many months apart. If the test were perfectly reliable, that is to say test scores were not influenced by any random error, then respondents would be expected to obtain the same score on each occasion, as their level of reasoning ability would not have changed between the two points in time when they completed the test. In this way, the extent to which respondents’ scores are unstable over time can be used to estimate the test’s reliability. Stability coefficients provide an important indicator of a test’s likely usefulness. If these coefficients are low, then this suggests that the test is not a reliable measure and is therefore of little practical use for assessment and selection and assessment purposes.








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