CNN's Walter Upgreave today made clear why taking investment advice from the media is a bad idea. In his column today he takes a contrary view of "dollar cost averaging". The dead giveaway is this line: "But while dollar-cost averaging has risen to the level of accepted truth in many circles, it isn’t the magic bullet it’s made out to be. Indeed, some of the claims are simply an illusion ." Put another way, his job is to provide something interesting for us to read and repeating conventional wisdom won't get you many readers. But there is a reason why dollar cost averaging is conventional wisdom and Upgreave is doing a huge disservice by encouraging people to ignore it. Sometimes conventional wisdom is wrong, but, if you really understand the role of investment mix or dollar cost averaging in risk management, you realize that Upgreave's argument has no merit. Here is the nut of his argument: "Over the course of the year, you would have actually ...