Correlation coefficients can mean a positive, ... This article explains the significance of linear correlation coefficients for investors, ... In the chart below, ...

Thus, if we calculate the correlation coefficient including this outlier, it would suggest a weaker correlation between the stock and the S&P 500 than actually exists on most trading days.

The graph below plots three common versions of the phrase going back to 1880 as they turn up in Google Books. It’s that right-most rise that interests me—the explosion of correlations that don ...