Continuity correlation coefficients represent how well a scatter-plot of points relating early aggression to later aggression can be “fit’ by a straight line, but there are always discrepancies from the average trend—individuals who start out aggressive and end up nonaggressive and vice versa. These discrepancies may be distributed normally over the range of aggression or they may be particularly notable at the low or high end of the range. The same overall correlation can be produced with quite different such distributions. This has led to disagreements over what the obtained statistical continuity actually represents. As noted earlier, some researchers have argued that the statistical continuity of aggression over time is owing to a few highly aggressive people [Loeber, 1982; Moffitt, 1990], which has led Moffitt [1993] to present a taxonomy of adolescent-limited vs. life-course-persistent antisocial behavior. According to Moffitt, only a small group of individuals exhibit high levels of aggression across time points, and this group accounts for the moderate levels of statistical continuity found across studies. For most other individuals, aggression is limited to one developmental period, particularly adolescence.
