title: Microrandomized trials: An experimental design for developing just-in-time adaptive interventions.
abstract: OBJECTIVE
  This article presents an experimental design, the microrandomized trial, developed to support optimization of just-in-time adaptive interventions (JITAIs). JITAIs are mHealth technologies that aim to deliver the right intervention components at the right times and locations to optimally support individuals' health behaviors. Microrandomized trials offer a way to optimize such interventions by enabling modeling of causal effects and time-varying effect moderation for individual intervention components within a JITAI.
  
  
  METHODS
  The article describes the microrandomized trial design, enumerates research questions that this experimental design can help answer, and provides an overview of the data analyses that can be used to assess the causal effects of studied intervention components and investigate time-varying moderation of those effects.
  
  
  RESULTS
  Microrandomized trials enable causal modeling of proximal effects of the randomized intervention components and assessment of time-varying moderation of those effects.
  
  
  CONCLUSIONS
  Microrandomized trials can help researchers understand whether their interventions are having intended effects, when and for whom they are effective, and what factors moderate the interventions' effects, enabling creation of more effective JITAIs.
authors.affiliation: School of Information, University of Michigan.
authors.forename: Predrag
authors.identifier: 0000-0002-4570-703X
authors.initials: P
authors.lastname: Klasnja
authors.affiliation: School of Nutrition and Health Promotion, Arizona State University.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Hekler
authors.affiliation: Department of Psychology, University of Pittsburgh.
authors.forename: Saul
authors.initials: S
authors.lastname: Shiffman
authors.affiliation: Department of Statistics, University of Michigan.
authors.forename: Audrey
authors.initials: A
authors.lastname: Boruvka
authors.affiliation: Institute of Social Research, University of Michigan.
authors.forename: Daniel
authors.initials: D
authors.lastname: Almirall
authors.affiliation: Department of Statistics, University of Michigan.
authors.forename: Ambuj
authors.initials: A
authors.lastname: Tewari
authors.affiliation: Department of Statistics, University of Michigan.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Murphy
mesh_terms: D000223:Adaptation, Psychological; D061345:Early Medical Intervention / Q000379:methods* / Q000639:trends; D015438:Health Behavior; D006801:Humans; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D012107:Research Design / Q000592:standards; D017216:Telemedicine / Q000379:methods* / Q000639:trends