title: Twitter sentiment predicts Affordable Care Act marketplace enrollment.
abstract: BACKGROUND
  Traditional metrics of the impact of the Affordable Care Act (ACA) and health insurance marketplaces in the United States include public opinion polls and marketplace enrollment, which are published with a lag of weeks to months. In this rapidly changing environment, a real-time barometer of public opinion with a mechanism to identify emerging issues would be valuable.
  
  
  OBJECTIVE
  We sought to evaluate Twitter's role as a real-time barometer of public sentiment on the ACA and to determine if Twitter sentiment (the positivity or negativity of tweets) could be predictive of state-level marketplace enrollment.
  
  
  METHODS
  We retrospectively collected 977,303 ACA-related tweets in March 2014 and then tested a correlation of Twitter sentiment with marketplace enrollment by state.
  
  
  RESULTS
  A 0.10 increase in the sentiment score was associated with an 8.7% increase in enrollment at the state level (95% CI 1.32-16.13; P=.02), a correlation that remained significant when adjusting for state Medicaid expansion (P=.02) or use of a state-based marketplace (P=.03).
  
  
  CONCLUSIONS
  This correlation indicates Twitter's potential as a real-time monitoring strategy for future marketplace enrollment periods; marketplaces could systematically track Twitter sentiment to more rapidly identify enrollment changes and potentially emerging issues. As a repository of free and accessible consumer-generated opinions, this study reveals a novel role for Twitter in the health policy landscape.
authors.affiliation: Robert Wood Johnson Foundation Clinical Scholars Program, University of Pennsylvania, Philadelphia, PA, United States. charwong@upenn.edu.
authors.forename: Charlene A
authors.identifier: http://orcid.org/0000-0003-0246-9040
authors.initials: CA
authors.lastname: Wong
authors.forename: Maarten
authors.identifier: http://orcid.org/0000-0002-0701-4654
authors.initials: M
authors.lastname: Sap
authors.forename: Andrew
authors.identifier: http://orcid.org/0000-0002-6383-3339
authors.initials: A
authors.lastname: Schwartz
authors.forename: Robert
authors.identifier: http://orcid.org/0000-0003-4332-9343
authors.initials: R
authors.lastname: Town
authors.forename: Tom
authors.identifier: http://orcid.org/0000-0002-0876-2312
authors.initials: T
authors.lastname: Baker
authors.forename: Lyle
authors.identifier: http://orcid.org/0000-0003-2047-1443
authors.initials: L
authors.lastname: Ungar
authors.forename: Raina M
authors.identifier: http://orcid.org/0000-0002-9801-6881
authors.initials: RM
authors.lastname: Merchant
mesh_terms: D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D058991:Patient Protection and Affordable Care Act / Q000706:statistics & numerical data*; D061108:Social Media / Q000706:statistics & numerical data*; D014481:United States
keywords: affordable care act; health insurance marketplace; social media