In this work, two new coefficients have been proposed: the Coefficient of Proportional Variance (Cpv) and the Coefficient of Content Validity (Ccv). The Coefficient of Proportional Variance proposes a solution to the problem of measuring and evaluating the relative variability of a given distribution, obviating the problems of subjective interpretation and value judgments. The mathematical relationship derived from the Cpv allows for a more precise and more scientific interpretation of relative variability of data. The Coefficient of Content Validity permits the calculation of the content validity for each item, as well as the total content validity, of any data collection instrument that has been subjected to the evaluation of several judges (Panel of Experts Technique). Until now, according to the psychometric and statistical literature, a quantitative estimator of the content validity of a measuring instrument had not been achieved.