Yujin Heo

Date of Award

Summer 2023

Document Type

Open Access Dissertation


School of Journalism and Mass Communications

First Advisor

Robert McKeever

Second Advisor

Sei-Hill Kim


The purpose of this dissertation is to explore the intermedia agenda-setting interplay between traditional news media and Twitter in the wake of mass shooting incidents. Applying Latent Dirichlet Allocation (LDA) topic modeling to data sourced from Twitter, national, and local news, the study investigated the distinct coverage patterns and the extent of their reciprocal influence over time. The findings of this study demonstrated that, in the immediate aftermath of a shooting incident, national news outlets exerted a significant agenda-setting influence on both local media and Twitter discourse. However, as time unfolds, a mutually influential dynamic emerged across all media platforms. Moreover, the study revealed discernible differences in content focus across these platforms: traditional media tended to address broader societal issues related to such incidents, whereas Twitter discourse placed a pronounced emphasis on victims and policy advocacy, notably in the context of mental health funding. These insights underscore the complexity and dynamism inherent in our rapidly evolving media ecosystem. The results were discussed concerning their implications for advancing agenda-setting research, with due consideration given to potential limitations and suggestions for future inquiries.


© 2023, Yujin Heo