| We examined theoretical, methodological and statistical problems involved in evaluating the outcome of aggression on the playground for a universal preventive intervention for conduct disorder. Moderately aggressive children were hypothesized most likely to benefit. Aggression was measured on the playground using observers blind to the group status of the children. Behavior was microcoded in real time to minimize potential expectancy biases. The effectiveness of the intervention was strongly related to initial levels of aggressiveness. Models that incorporated corrections for low reliability (the ratio of variance due to true time-stable individual differences to total variance) and censoring (a floor effect in the rate data due to short periods of observation) obtained effect sizes five times larger than models without such corrections with respect to |
Updated 05/20/2006