What is validity? What is reliability? Discuss the relationship can a measure be valid, but not reliable? Reliable but not valid? Explain. Solution ; The term validity is defined as the accuracy of the interpretations which we can make out from the test scores On the other hand Reliability is defined as the the consistency or stability of the test scores No a measure cannot be valid unless it is reliable.It has to be reliable first in order to be valid .On the other hand the measure can be reliable but not valid.The measure can be consistent without any accuracy..