Since Feb. 27, the day before the Iran war started, gold prices have tumbled about 18%. That's difficult to square with the widespread belief that gold is a hedge against geopolitical risk. Gold investors shouldn't be surprised. None of the factors that that are widely assumed to be correlated with gold rests on a strong statistical foundation. Gold instead marches to its own drummer. Perhaps gold's decline is an exception to the historical rule. To find out, I calculated the correlation between bullion's monthly changes and that of the Geopolitical Risk, or GPR, index. This index, created by Dario Caldara and Matteo ... (full story)