On an Identity for the Variance of a Ratio of Two Random Variables
J. C. Koop · Journal of the Royal Statistical Society Series B (Statistical Methodology) · 1964
Summary A new identity showing the relationship between the variance of the ratio of two random variables and the variance of the random variable in the numerator of the ratio is presented. For any sample design the identity offers a basis for exploring the conditions under which ratio estimators have smaller variance than linear estimators.