In uniaxial tensile tests of low-carbon steel sheets conducted by Stickels and Mould, the directional dependence of the r-value (a material parameter used in metal forming) and of the Young's modulus (an elastic constant) were found to be correlated. This phenomenon is sometimes called "correlation of elastic and plastic anisotropy" in the literature. In this talk I will present a simple theory that explains the physical basis behind this phenomenon, which will serve also as an introduction to quantitative texture analysis in metal forming.