It relates to the correct applicability of the instrument/test/procedure in a needed situation It refers to the reproducibility of the results when repeated measurements are done It refers to the ability of the instrument/test to measure what it is supposed to measure Reliability refers to the degree to which assessment tool produces consistent results, when repeated measurements are made. Validity implies the extent to which the research instrument measures, what it is intended to measure.
Here you have all the major differences between Validity and Reliability and what it actually means: VALIDITY
