Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Covariance indicates the relationship ...

Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

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 ...

A coefficient to measure association between two random variables, each distributed on the surface of the unit sphere in p-dimensional space, is proposed, analogous to an existing correlation ...

An important part of the identification and diagnostic checking of space-time ARMA models is the evaluation of the significance of the autocorrelations of the observations and residuals, respectively.