Reliability does not imply validity. That is, a reliable measure that is measuring something consistently is not necessarily measuring what you want 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 a more accurate way of describing precision, while validity is a more precise way of describing accuracy. While reliability does not imply validity, a lack of reliability does place a limit on the overall validity of a test. A test that is not perfectly reliable cannot be perfectly valid, either as a means of measuring attributes of a person or as a means of predicting scores on a criterion. While a reliable test may provide useful valid information, a test that is not reliable cannot possibly be valid.[4] An example often used to illustrate the difference between reliability and validity in the experimental sciences involves a common bathroom scale. If someone who is 200 pounds steps on a scale 5 times and gets readings of 15, 250, 95, 140, and 500, then the scale is not reliable. If the scale consistently reads 150, then it is reliable, but not valid. If it reads 200 each time, then the measurement is both reliable and valid.-( yenthu vayichallum evidey okkeyoo yenghanney okkeyoo striking my mind.)
Posted on: Tue, 05 Nov 2013 15:55:27 +0000
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