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Multiphase Optimization Strategy (MOST)

Overview: The Multiphase Optimization Strategy (MOST) is a research framework, based in engineering principles, for determining the most efficient and effective version of an intervention. It assesses the effectiveness of individual program elements and considers whether effectiveness varies depending on context. MOST consists of three phases:

  1. Preparation: Researchers define or refine the conceptual model, identify theoretical active ingredients, and select criteria to guide the structure and decision points of the study.
  2. Optimization: Researchers selects specific intervention components and levels of intensity—for example, number of sessions or duration of sessions—that they believe will optimize the intervention. Researchers then test these components through designs such as factorial experiments, SMARTs, or micro-randomized trials. The goal is to learn how to design the intervention that provides the best results in an efficient, scalable way.
  3. Evaluation: Researchers conduct a randomized control trial (RCT) of the optimized intervention to confirm the effectiveness. If the intervention is not effective, researchers return to the preparation phase and begin the MOST cycle again.


Hallmarks: Compared to traditional RCTs, MOST—

  • Provides a research and development framework to determine the active ingredients empirically proven to be responsible for changes in specific outcomes and to find the most efficient, scalable combination of these ingredients.
  • Helps researchers consider the effectiveness of individual and combined active ingredients in: achieving specific outcomes for all participants; improving results in a specific context or with subgroups of families; and finding cost-efficiencies.


Benefits for Precision Home Visiting: MOST is a research framework that allows for the identification of efficient and scalable interventions. MOST prioritizes testing the effectiveness of active ingredients in home visiting interventions and finding the most effective combination of active ingredients to improve specific outcomes. Home visiting researchers and programs may find MOST helpful for determining the best combination of intervention components based on families’ unique characteristics and contexts.



  • Penn State: The Methodology Center. (2018). Overview of MOST. Retrieved from
  • Collins, L. M., Kugler, K. C., & Gwadz, M. V. (2015). Optimization of multicomponent behavioral and biobehavioral interventions for the prevention and treatment of HIV/AIDS. Aids Behavior, Supp 1, 197-214.
  • Guastaferro, K. (2018). The Multiphase Optimization Strategy (MOST). Presentation from the HARC 2018 Methods Meeting, Chicago, IL. Retrieved from