Rise of single-case experimental designs: A historical overview of the necessity of single-case methodology

ABSTRACT

Windelband ([1894]1980) advocated that two approaches are used for accumulating scientific knowledge. The first is the idiographic approach that derives knowledge from a single unit, and the second is the nomothetic approach that accumulates knowledge of a group. Given these two approaches, the former matches case studies while the latter is more appropriate with experimental group studies. Scientists have criticized both methodologies for their various limitations. Later, the single-case methodology emerged as an alternative that potentially allays these limitations. In this context, this narrative review aims to describe the historical roots of single-case experimental designs (SCEDs) that have emerged to eliminate the tension of nomothetic and idiographic approaches over time. First, the review focuses on the emergence of SCEDs. Second, the strengths and challenges of SCEDs are reviewed, including those to address the limitations of group experimental and case studies. Third, the use and analyses of SCEDs are outlined, considering their current status. Fourth, this narrative review continues to delineate the dissemination of SCEDs in the modern scientific world. As a result, SCEDs can be evaluated as a method that has the potential to overcome the issues encountered in case description and group experimental research. Thus, that helps accumulate nomothetic and idiographic knowledge in determining evidence-based practices.

KEYWORDS:

• Single-case experimental designs
• Evidence-based practices
• Nomothetic
• Idiographic
• Historical overview

Acknowledgement

The author greatly thanks the editor Dr. Robyn Tate and the reviewers for their constructive suggestions for improving the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Investigations are available in Freud’s book entitled “A General Introduction to Psychoanalysis” in 1943.

2 Titchener and Geissler’s (1908) article presents a bibliography of the scientific writings of Wilhelm Wundt.

3 Thorndike’s monographs can be viewed at https://doi.org/10.1037/h0092987.

4 The English translation of Ebbinghaus’s book entitled “Memory: A Contribution to Experimental Psychology” can be viewed at https://web.archive.org/web/20050504104838/http://psy.ed.asu.edu/~classics/Ebbinghaus/index.htm.

5 Neo-Galtonian science can be explored further in Danziger’s (1994) book.

6 COPE is a non-profit agency established to educate and support reviewers, editors, and publishers for ethical publication policies. The committee, which started its first activities in 1997, has approximately five thousand peer-reviewed journal members in the fields of education, psychology, and medicine as of today. Visit for detailed information: https://publicationethics.org.

7 The information presented here is a general rule. Readers can look to Brysbaert’s or Prajapati et al.’s article for more detailed information on the required sample size for statistical power of parametric and nonparametric tests.

8 Note that higher scores represent better performance in Figure 1(a) and (c), whereas lower scores represent better performance in Figure 1(b).