Abstract
The goal of this manuscript is to describe strategies for maximizing the yield of data from small samples in prevention research. We begin by discussing what “small” means as a description of sample size in prevention research. We then present a series of practical strategies for getting the most out of data when sample size is small and constrained. Our focus is the prototypic between-group test for intervention effects; however, we touch on the circumstance in which intervention effects are qualified by one or more moderators. We conclude by highlighting the potential usefulness of graphical methods when sample size is too small for inferential statistical methods.
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Notes
Our focus on statistical power assumes a traditional null hypothesis statistical testing (NHST) approach to data analysis. We recognize the shortcomings of this approach and its frequent misuse; however, because it remains the primary approach to the analysis of data from prevention trials, it is the approach on which our analysis and recommendations focus. For readers interested in concerns about NHST and potential alternatives, Nickerson (2000) and Harlow et al. (1997) provide balanced, largely nontechnical presentations.
See von Hippel (2013) for potential problems and solutions for use of these methods with small samples.
An informative discussion of the use of covariates to increase statistical power is provided by Dennis et al. (2009).
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Acknowledgments
During the writing of this manuscript, the authors were supported by National Institute on Drug Abuse (NIDA) Grant P30 DA023026. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIDA.
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The authors declare that they have no conflict of interest.
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Hopkin, C.R., Hoyle, R.H. & Gottfredson, N.C. Maximizing the Yield of Small Samples in Prevention Research: A Review of General Strategies and Best Practices. Prev Sci 16, 950–955 (2015). https://doi.org/10.1007/s11121-014-0542-7
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DOI: https://doi.org/10.1007/s11121-014-0542-7