WIDE\" U 0 Averages and indexes differ from one another in that an index . is the arithmetic average price behavior of a group of stocks at a given point in time. . measures the current price behavior of a group of stocks in relation to a base value set at an earlier point in time. . is of value in-and-of itself, whereas an average must be compared to a historical gure to have any meaning. . always moves up before a corresponding average moves up, and always moves down before a corresponding average moves down