standard deviation

standard deviation　标准　

1.investment：measure of the variability（volatility）of a sesecurity，derived from the security’s historical returns，and used in determining the range of possible future returns.The higher the standard deviation，the greater the potential for volatility.2.marketing：measure of the difference between an average（arithmetic mean）and the individual values included in the average，such as the variation between the responses to the same advertisement in different media vehicles.3.statistics：measure of the unpredictability of a random variable，expressed as the average deviation of a set of data from its arithmetic mean and computed as the positive square root of the variance.