Rating the Valence of Media Content about Electronic Cigarettes Using Crowdsourcing: Testing Rater Instructions and Estimating the Optimal Number of Raters

Electronic cigarettes (e-cigarettes) are a controversial public health topic due to their increasing popularity among youth and the uncertainty about their risks and benefits. Researchers have started to assess the valence of media content about e-cigarette use, mostly using expert coding. The current study aims to offer a methodological framework and guideline when using crowdsourcing to rate the valence of e-cigarette media content....