Assessment & Research

"An analysis-of-variance model for intrasubject replicaiton design": some additional comments.

Thoresen et al. (1974) · Journal of applied behavior analysis 1974
★ The Verdict

Drop ANOVA for single-case data—serial correlation breaks the math, so use time-series or mixed-effects instead.

✓ Read this if BCBAs who run reversal or multiphase designs and want defensible stats.
✗ Skip if Practitioners who rely only on visual inspection and never compute p-values.

01Research in Context

01

What this study did

Mulvaney et al. (1974) wrote a short, sharp note about numbers.

They looked at how people were using ANOVA on single-subject reversal designs.

The authors said that ANOVA misses the point because the data points are linked over time.

02

What they found

The paper says ANOVA treats each score as independent.

In real ABA graphs, yesterday’s score shapes today’s score.

They urge us to swap ANOVA for time-series tests that handle this serial correlation.

03

How this fits with other research

Christophersen et al. (1972) had pushed the opposite view: ANOVA is fine for reversal data.

Mulvaney et al. (1974) and Lydersen et al. (1974) answer together—both reject that stance, forming a direct-replication pair that warns the same year.

DeHart et al. (2019) extends the warning by showing mixed-effects models give the same benefit without old ANOVA baggage.

Dodd (1984) later offered the simple C-statistic as a time-series tool, proving the idea stayed alive.

04

Why it matters

If you graph one client’s behavior across phases, do not run a one-way ANOVA in Excel.

Use visual analysis first; if you need stats, pick time-series or mixed-effects options that respect the order of sessions.

This keeps your conclusions honest and your graphs clean.

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→ Action — try this Monday

Open your last reversal graph and delete any ANOVA table—replace it with a mixed-effects or C-statistic test if you need numbers.

02At a glance

Intervention
not applicable
Design
theoretical
Finding
not reported

03Original abstract

The fixed effects ANOVA procedure utilized by Gentile, Roden, and Klein (1972) for single subjects is found inappropriate. Hartmann's proposal of a one-way fixed-effect ANOVA model is also considered. Time series analysis that takes serial correlation effects into account is recommended.

Journal of applied behavior analysis, 1974 · doi:10.1901/jaba.1974.7-639