Hi Fawad;

Take a look Standarts for educational and psychological testing book (AERA, APA & NCME, 2014).

Good luck.

The layman explanation is: the tests are meant to show whether or not the instrument in question — which you intend to give to people — can measure what it is originally meant to measure without distortion or bias to any of person filling it.

If you don’t report them, nobody knows whether the values you report, measured with the instrument in question, can be trusted or not.

You could use just about any introductory textbook as a reference for the importance of both reliability and validity. In other words, there is such a widespread and longstanding consensus on this issue that it does not require any citation to justify it.

In terms of what the two indicators accomplish, reliability tell you how much reliable (i.e., non-random) variance you have in a scale. If it is unreliable (i.e., has a great deal of random variation), then it will by definition be unable to correlate with any other variables.

With regard to validity, this refers to the extent to which an instrument does indeed measure what it was supposed to measure. Without evidence of validity, your instrument could be a measure of almost anything (i.e., it could be "confounded" with other measures).

Thanks Abdullah, Mohammed, and David. Really value your opinion.

You report them so that I, as your reader/listener, know how much value to put into your results. If your measurement is garbage, your results are garbage. Why should I pay attention to your results if they are garbage. This does not need a citation from the literature. There is such a consensus that this is now common sense.