Relationship between Validity and Reliability of a test,

Reliability and validity are two different standards used to gauge the usefulness of a test. Though different, they work together. It would not be beneficial to design a test with good reliability that did not measure what it was intended to measure. The inverse, accurately measuring what we desire to measure with a test that is so flawed that results are not reproducible, is impossible. Reliability is a necessary requirement for validity. This means that you have to have good reliability in order to have validity. Reliability actually puts a cap or limit on validity, and if a test is not reliable, it cannot be valid. Establishing good reliability is only the first part of establishing validity. Validity has to be established separately. Having good reliability does not mean we have good validity, it just means we are measuring something consistently. Now we must establish, what it is that we are measuring consistently. The main point here is reliability is necessary but not sufficient for validity. In short we can say that reliability means noting when the problem is validity.