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Commentary Open Access

Single-Case Intervention Research in the Health Sciences: Randomization + Replication = Respectability (Almost)

  • 1University of Arizona, USA
  • 2University of Wisconsin – Madison, USA
+ Affiliations - Affiliations

Corresponding Author

Joel R. Levin, jrlevin@arizona.edu

Received Date: November 19, 2025

Accepted Date: January 21, 2026

Abstract

Elaboration and extensions are provided of an earlier article on the application of time-series-based single-case intervention designs (SCIDs) and analyses for researchers in the health sciences. The research potential, as well as the strengths and weaknesses of such designs, are detailed. In this Comment we expand on the argument that the scientific credibility of SCIDs can be considerably enhanced through a researcher’s incorporation of various randomization and replication procedures, attention to unwanted operational effects, along with the adoption of appropriate data-analysis methods.

Keywords

Single-case intervention research, Randomization, Replication, Operational issues, Internal validity, External validity, Construct validity, Researcher and patient bias, Statistical conclusion validity, Scientific credibility

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