From George Cooper's The Origin of Financial Crises: Central Banks, Credit Bubbles, and the Efficient Market Fallacy (Vintage)
:
:Technically, because asset prices generally cannot become negative, when a price gets close to zero the size of the next possible price decline becomes a little smaller than the size of the next possible price rise. By making this adjustment the normal probability distributions, which are discussed in the rest of this book, become log normal probability distributions. For all practical purposes you can, if you have not already done so, forget this piece of information.The book, by the way, is very good.
