Skip to main content
. Author manuscript; available in PMC: 2022 Dec 6.
Published in final edited form as: Psychol Methods. 2022 Jan 13;27(5):874–894. doi: 10.1037/met0000283

Table 1.

Key Considerations When Designing an MRT.

Conceptual framework:

  • Specify how each intervention component is designed to affect distal outcomes via the proximal outcomes; the proximal outcomes are part of the hypothesized causal process through which the intervention is intended to work.

Components to Examine Experimentally:

  • An experimental component can represent any aspect of an intervention that can be separated out for study.

  • Constant components are components that do not require experimentation.

Randomization:
  • Micro-randomization. Suitable when the goal is to optimize a JITAI (construct decision rules, ascertain tailoring variables).
    • Randomization probabilities may reflect burden considerations. For example, in implementation over x months, if around y push interventions per day/month would constitute an acceptable level of burden for individuals, then the choice of the randomization probability will be informed by this consideration.

  • Baseline randomization. Suitable for already constructed component options of all types (JITAI, non-adaptive, time-varying, non-time-varying). For example, randomization at baseline between two well defined JITAI options (each with prespecified decision rules and tailoring variables).

MRT Design Impacts JITAI Design:

  • If observations of context are used to restrict the feasible intervention component options (e.g., if the individual is driving, then the only feasible option is “do nothing”) then data from the MRT is only useful for developing JITAIs that incorporate the same restrictions.

  • The decision points in the MRT should include all possible decision points considered in the JITAI design.

Measurement of Outcomes:

  • The duration over which the proximal outcome is measured is an important consideration: too long a duration and the effect of the options will have decayed; too short a duration and the effect may not have yet occurred.

Sample size: