A standardized mean difference effect size for single case designs

Authors

Larry V. Hedges

James E. Pustejovsky

William R. Shadish

Published

August 14, 2012

Single case designs are a set of research methods for evaluating treatment effects by assigning different treatments to the same individual and measuring outcomes over time and are used across fields such as behavior analysis, clinical psychology, special education, and medicine. Emerging standards for single case designs have focused attention on the need for effect sizes for summarizing and meta-analyzing findings from the designs; although many effect size measures have been proposed, there is little consensus regarding their use. This article proposes a new effect size measure for single case research that is directly comparable with the standardized mean difference (Cohen’s d) often used in between-subjects designs. Techniques are provided for estimating the new effect size, as well as its variance, from balanced or unbalanced treatment reversal designs. The proposed estimation methods are further evaluated using a simulation study and then demonstrated in two applications.

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Citation

BibTeX citation:
@article{hedges2012,
  author = {Hedges, Larry V. and Pustejovsky, James E. and Shadish,
    William R.},
  title = {A Standardized Mean Difference Effect Size for Single Case
    Designs},
  journal = {Research Synthesis Methods},
  volume = {3},
  pages = {224-239},
  date = {2012-08-14},
  url = {https://dx.doi.org/10.1002/jrsm.1052},
  doi = {10.1016/j.jsp.2018.02.003},
  langid = {en}
}
For attribution, please cite this work as:
Hedges, L. V., Pustejovsky, J. E., & Shadish, W. R. (2012). A standardized mean difference effect size for single case designs. Research Synthesis Methods, 3, 224–239. https://doi.org/10.1016/j.jsp.2018.02.003