Intervention Effectiveness of The Incredible Years: New Insights into Sociodemographic and Intervention-based Moderators

Research paper by Joyce Weeland, Rabia R. Chhangur, Danielle van der Giessen, Walter Matthys, Bram Orobio de Castro, Geertjan Overbeek

Indexed on: 05 Oct '16Published on: 23 Aug '16Published in: Behavior Therapy


We tested the effectiveness of the preventive behavioral parent training (BPT) The Incredible Years (IY) and the independent effects of previously suggested sociodemographic and intervention-based moderator variables (i.e., initial severity of externalizing problem behavior, child gender, social economic status, family composition, and number of sessions parents attended), in a large scaled randomized-controlled-trial. Questionnaire and observation data from 387 parents and children aged 4-8 years (Mage = 6.21, SD = 1.33; 55.30 % boys) across pretest, posttest, and 4-month follow-up, were analyzed, using full intention-to-treat analyses and correcting for multiple testing. IY was successful in decreasing parent-reported child externalizing behavior (Cohen’s d = .20 at posttest; d = .08 at follow-up), increasing parent-reported (d = .49; d = .45) and observed (d = .06; d = .02) positive parenting behavior, and decreasing parent-reported negative parenting behavior (d = .29; d = .25). No intervention effects were found for reported and observed child prosocial behavior, observed child externalizing behavior, and observed negative parenting behavior. Out of 40 tested moderation effects (i.e., eight outcomes times five moderators), only three significant moderation effects appeared. Thus, no systematic evidence emerged for moderation of IY effects. The present multi-informant trial demonstrated that many previously suggested moderators might not be as potent in differentiating BPT effects as once thought.

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