Harry Markowitz famously quipped that diversification is the only free lunch in investing. What he did not say is that this is only true if correlations are known and stable over time. Markowitz’s ...

X ij = [x ij1, ... , x ijp]' The Generalized Estimating Equation of Liang and Zeger (1986) for estimating the p ×1 vector of regression parameters is an extension of the independence estimating ...

Elvis Picardo is a regular contributor to Investopedia and has 25+ years of experience as a portfolio manager with diverse capital markets experience. A negative correlation means that two variables ...