Do Longitudinal Trends in Tobacco 21-Related Media Coverage Correlate with Policy Support? an Exploratory Analysis Using Supervised and Unsupervised Machine Learning Methods.

Media coverage can impact support for health policies and, ultimately, compliance with those policies. Prior research found consistent, high support for Tobacco 21 policies, which raise the minimum legal age of tobacco purchase to 21, among adults and nonsmoking youth. However, a recent study found support (i.e., agreement with the statement: "The legal age to buy tobacco cigarettes should be increased from 18 to 21") among 13-20-year-old smokers increased from 2014 until mid-2016 and then declined steadily through mid-2017. To assess whether media coverage could be related to young smokers' changing support, we conducted an exploratory content analysis to identify texts about Tobacco 21 in a large corpus of tobacco texts (N = 135,691) published in four popular media sources from 2014 to 2017. For this content analysis, we developed a novel methodological approach that combined supervised and unsupervised machine learning methods and could be useful in other areas of communication research. We found that the prevalence of Tobacco 21 media coverage and Tobacco 21 support among young smokers exhibited similar temporal patterns for much of the study period. These findings highlight the need for continued research into the effects of media coverage on Tobacco 21 support among young smokers, a group that must comply with Tobacco 21 policies in order to ensure maximum effectiveness. This research is of particular utility following the 2019 passage of a federal Tobacco 21 regulation, as the public health impact of this regulation could be limited by low public support, and thus low rates of policy compliance.