Reliability and validity statistics in oral health research

Whenever we observe or measure, we are concerned with whether we are measuring what we intend to measure or whether our observations are influenced by the circumstances in which they are made and we reach conclusions about the quality of our measures conclusions that will play an important broader role in addressing the substantive issues of our study.A good measure must not only be reliable but also valid. We often think of reliability and validity as separate ideas but, in fact, they're related to each other. A measure can not be valid unless it is reliable, but a reliable measure may not be valid, and 'Reliability is a necessary but not sufficient condition for validity'.