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Single-case experimental designs: the importance of randomization and replication

Single-case experimental designs are rapidly growing in popularity. This popularity needs to be accompanied by transparent and well-justified methodological and statistical decisions. Appropriate experimental design including randomization, proper data handling and adequate reporting are needed to ensure reproducibility and internal validity. The degree of generalizability can be assessed through replication.

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  1. Kazdin, A. E. Single-case experimental designs: characteristics, changes, and challenges. J. Exp. Anal. Behav. 115, 56–85 (2021).

    Article  Google Scholar 

  2. Shadish, W. & Sullivan, K. J. Characteristics of single-case designs used to assess intervention effects in 2008. Behav. Res. 43, 971–980 (2011).

    Article  Google Scholar 

  3. Tanious, R. & Onghena, P. A systematic review of applied single-case research published between 2016 and 2018: study designs, randomization, data aspects, and data analysis. Behav. Res. 53, 1371–1384 (2021).

    Article  Google Scholar 

  4. Ferron, J., Foster-Johnson, L. & Kromrey, J. D. The functioning of single-case randomization tests with and without random assignment. J. Exp. Educ. 71, 267–288 (2003).

    Article  Google Scholar 

  5. Michiels, B., Heyvaert, M., Meulders, A. & Onghena, P. Confidence intervals for single-case effect size measures based on randomization test inversion. Behav. Res. 49, 363–381 (2017).

    Article  Google Scholar 

  6. Aydin, O. Characteristics of missing data in single-case experimental designs: an investigation of published data. Behav. Modif. (2023).

    Article  Google Scholar 

  7. De, T. K., Michiels, B., Tanious, R. & Onghena, P. Handling missing data in randomization tests for single-case experiments: a simulation study. Behav. Res. 52, 1355–1370 (2020).

    Article  Google Scholar 

  8. Baek, E., Luo, W. & Lam, K. H. Meta-analysis of single-case experimental design using multilevel modeling. Behav. Modif. 47, 1546–1573 (2023).

    Article  Google Scholar 

  9. Michiels, B., Tanious, R., De, T. K. & Onghena, P. A randomization test wrapper for synthesizing single-case experiments using multilevel models: a Monte Carlo simulation study. Behav. Res. 52, 654–666 (2020).

    Article  Google Scholar 

  10. Tate, R. L. et al. The single-case reporting guideline in behavioural interventions (SCRIBE) 2016: explanation and elaboration. Arch. Sci. Psychol. 4, 10–31 (2016).

    Google Scholar 

Download references


R.T. and J.W.S.V. disclose support for the research of this work from the Dutch Research Council and the Dutch Ministry of Education, Culture and Science (NWO gravitation grant number 024.004.016) within the research project ‘New Science of Mental Disorders’ ( R.M. discloses support from the Generalitat de Catalunya’s Agència de Gestió d’Ajusts Universitaris i de Recerca (grant number 2021SGR00366).

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Correspondence to René Tanious.

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Tanious, R., Manolov, R., Onghena, P. et al. Single-case experimental designs: the importance of randomization and replication. Nat Rev Methods Primers 4, 27 (2024).

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