This graph tells a very simple tale. Between 1997 and 2007, the rate of autism and organic food sales has risen at the same rate. Obviously, this chart goes to prove that autism and eating organic ...

In the first case, there is a strong upward-sloping relationship between X and Y; in the second case, no apparent relationship; in the third case, a strong downward-sloping relationship. Note the ...

Elvis Picardo is a regular contributor to Investopedia and has 25+ years of experience as a portfolio manager with diverse capital markets experience. Yarilet Perez is an experienced multimedia ...

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 ...

Correlation coefficients are indicators of the strength of the linear relationship between two different variables, x and y. A linear correlation coefficient that is greater than zero indicates a ...