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Studies with staggered starts: multiple baseline designs and group-randomized trials.
Dale A Rhoda1, David M Murray, Rebecca R Andridge
1Centers for Public Health Research and Evaluation, Battelle Memorial Institute, Columbus, OH 43201, USA. RhodaD@battelle.org
American Journal of Public Health
|September 24, 2011
Summary
Multiple baseline designs (MBDs) may complement, not replace, group-randomized trials (GRTs) in public health. While MBDs can offer statistical power, their effectiveness depends on specific conditions and careful evaluation for public health research.
Area of Science:
- Public Health Research Methodology
- Intervention Study Designs
- Statistical Power Analysis
Background:
- Multiple baseline designs (MBDs) are proposed as alternatives to group-randomized trials (GRTs).
- The applicability and effectiveness of MBDs in public health research require thorough examination.
- The impact of staggered starts on statistical power in GRTs is a critical consideration.
Purpose of the Study:
- To review the structural features of MBDs and assess their suitability for public health research.
- To evaluate the potential effectiveness of MBDs as an alternative to GRTs.
- To analyze the effect of staggered starts on statistical power in both MBDs and GRTs.
Main Methods:
- Systematic review of the MBD literature for key structural features and adoption suggestions in public health.
- Review of existing literature on statistical power in GRTs, particularly with staggered starts.
- Computation of statistical power for both MBDs and GRTs under various conditions.
Main Results:
- Structural features contributing to MBD success in other fields may not readily translate to public health settings.
- MBDs can potentially be more powerful than GRTs, but this is contingent on specific assumptions needing careful practical evaluation.
- Staggered starts in GRTs, while sometimes necessary, invariably increase trial duration and often cost.
Conclusions:
- MBDs are more likely to serve as a valuable complement to GRTs rather than a direct replacement.
- The decision to use MBDs or GRTs should consider their respective strengths, weaknesses, and the specific context of the public health intervention.
- Careful consideration of design features and statistical power is essential for robust public health research.
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