UNC Perceived Message Effectiveness: Validation of a Brief Scale

Background Interventionists commonly identify promising messages for health communication efforts based on audience members' ratings of perceived message effectiveness (PME). Purpose We sought to validate a new PME measure that improved on existing scales by focusing on the behavior and respondent, being brief, and having strong psychometric properties. Methods Participants were a national convenience sample of 999 adults and national probability samples of 1,692 adults and 869 adolescents recruited in 2015. Smokers and nonsmokers rated up to six brief messages about the chemicals in cigarette smoke on two PME scales. The first was the new three-item University of North Carolina (UNC) PME Scale that assessed effects perceptions. The second was an established six-item PME scale that assessed message perceptions. We examined the UNC PME Scale's psychometric properties and compared both scales using item factor analysis. Results The UNC PME Scale measured the same construct across multiple chemical messages (all factor loadings >= 0.86). It exhibited high reliability (>0.85) over very low to moderate levels of PME (z = -2.5 to 0.2), a range that is useful for identifying more promising messages. Samples of adults and adolescents showed a similar pattern of results. As expected, the UNC PME Scale was strongly positively correlated with message perceptions (r=.84). It also exhibited strong psychometric properties among participants regardless of education, reactance, sex, and smoking status. Discussion The UNC PME Scale reliably and validly measured PME among adults and adolescents from diverse groups. This brief scale may be used to efficiently evaluate candidate antismoking messages and may be suitable for adaptation to other health risk behaviors.