Randomization does not ensure baseline equivalence in small-sample motor learning studies, so unbalanced pre-tests can overstate random-practice benefits¶

Claim · All claims
Evidence · 1 study (2 entries) · theoretical r2–r3 · q1
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q1 i? Randomization alone does not guarantee baseline equivalence, especially in the small samples typical of CI research. → Ammar 2025 q1 i? Studies with unbalanced pre-tests can skew acquisition, retention and transfer comparisons, overstating the benefits of random practice. → Ammar 2025 (2)

Evidence¶

Ammar 2025¶

Ammar, A., Trabelsi, K., Salem, A., Jahrami, H., & Schöllhorn, W. I. (2025). Advancing Contextual Interference: Addressing Methodological Debates, Reflecting on Meta-Analytic Practices and Generalizability, and Guiding Future Directions in Motor Learning. Educational Psychology Review. https://doi.org/10.1007/s10648-025-10043-1

q1 · i? · theoretical · r2

Theoretical argument in the rebuttal section on baseline equivalence: the authors contend that without reporting or statistically verifying pre-test equivalence, equivalence remains an untested assumption. No empirical data are offered for this statement.

"However, randomization does not ensure baseline equivalence, par - ticularly in small-sample studies common in motor learning research."

Ammar 2025 (2)¶

Ammar, A., Trabelsi, K., Salem, A., Jahrami, H., & Schöllhorn, W. I. (2025). Advancing Contextual Interference: Addressing Methodological Debates, Reflecting on Meta-Analytic Practices and Generalizability, and Guiding Future Directions in Motor Learning. Educational Psychology Review. https://doi.org/10.1007/s10648-025-10043-1

q1 · i? · theoretical · r3

The authors argue that given small sample sizes and variability in the CI literature, baseline differences are especially impactful and pose a serious threat to internal validity. This is an authors' interpretive argument, not a tested result.

"Studies with unbalanced pre-tests can easily skew acquisition, retention and/or transfer comparisons, overstating the bene- fits of random practice."

Discussion¶

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