Methodology of the outcome evaluation of the VERB campaign.

This article summarizes the methods used in the outcome evaluation of the VERB campaign. The outcome evaluation was designed to measure the awareness and understanding of VERB among the target audience of children aged 9-13 years (tweens) and to determine the effect of VERB awareness on psychosocial and behavioral outcomes. Cohorts of tweens and parents were interviewed annually via a telephone survey (Youth Media Campaign Longitudinal Survey). The first cohort (baseline) was surveyed in 2002 prior to VERB advertising and was repeated annually through 2006. A second cohort was surveyed in 2004-2006. A third, cross-sectional sample was surveyed in 2006. Each cohort consisted of a nationally representative sample of tweens to enable generalizability to the nation as a whole. Propensity scoring was used to control for confounding influences. The outcomes were analyzed for dose-response effects (i.e., whether higher levels of awareness led to stronger effects) and overall awareness effects (i.e., the difference between tweens unaware of VERB and all tweens in the U.S.). Secular trends in tweens' physical activity during the life of the campaign were also examined. This article also discusses weighting and imputation, alternative analyses used to assess the adequacy of the propensity methods, and the challenges involved in media campaign evaluations.