Assessment & Research

Single‐case experimental designs: Characteristics, changes, and challenges

Kazdin (2021) · Journal of the Experimental Analysis of Behavior 2021
★ The Verdict

Single-case designs are legit science—use them with pride and explain them with ease.

✓ Read this if BCBAs who write treatment plans, present at IEPs, or publish case studies.
✗ Skip if RBTs who only run programs written by others.

01Research in Context

01

What this study did

Kazdin (2021) maps the past, present, and future of single-case experimental designs.

He shows how these designs track one person at a time while still giving solid science.

The paper lists hurdles that keep BCBAs from using the method more often.

02

What they found

The design is strong yet under-used in everyday practice.

Kazdin says we can fix this by better training and clearer reports.

03

How this fits with other research

Walker et al. (2021) back the same idea: you don’t need big groups to claim a finding works.

They add that repeating the same small study across places builds trust in the result.

Soto (2020) takes the logic into brain labs, proving the tool works outside clinic rooms.

Wilson et al. (2022) give a live demo, running a school study that follows Kazdin’s rules.

04

Why it matters

You already run repeated probes and watch one client change. That is a single-case design. Kazdin gives you the language to defend it in meetings and in notes. Read the paper, borrow the graphs, and feel sure your data count as real evidence.

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02At a glance

Intervention
not applicable
Design
methodology paper
Finding
not reported

03Original abstract

Tactics of Scientific Research (Sidman, 1960) provides a visionary treatise on single-case designs, their scientific underpinnings, and their critical role in understanding behavior. Since the foundational base was provided, single-case designs have proliferated especially in areas of application where they have been used to evaluate interventions with an extraordinary range of clients, settings, and target foci. This article highlights core features of single-case experimental designs, how key and ancillary features of the designs have evolved, the special strengths of the designs, and challenges that have impeded their integration in many areas where their contributions are sorely needed. The article ends by placing the methodological approach in the context of other research traditions. In this way, the discussion moves from the specific designs toward foundations and philosophy of science issues in keeping with the strengths of the person and book we are honoring.

Journal of the Experimental Analysis of Behavior, 2021 · doi:10.1002/jeab.638