Congruity, also called consistency or relevance, between an ad and its context has been studied by many researchers (e.g., Bee and Madrigal 2012; Moorman, Neijens, and Smit 2002). Ad-context congruity is defined as the matching of content, or the matching of an affective or emotional execution style or tone, in ads and media vehicles (Feltham and Arnold 1994; Kim and Sundar 2010; Moore, Stammerjohan, and Coulter 2005; Sharma 2000). For online video ads, we borrowed par- tial concepts from previous literature and defined ad-context congruity as thematic congruity. This definition indicates the
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degree to which a video is thematically similar to accompa- nying in-stream video ads.