The problem-size effect on fluency is slightly steeper for subtraction than addition problems¶

Claim · All claims
Evidence · 1 study · associational r2 · q3
Currency · newest study 2025 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i? A significant problem size by operation interaction (partial R2 = 0.007) showed the slope of the problem size effect was slightly greater for subtraction problems. → Ethan Roy 2025

Evidence¶

Ethan Roy 2025¶

Ethan Roy, Mathieu Guillaume, Amandine Van Rinsveld, Project iLead Consortium & Bruce D. McCandliss. (2025). Tablet-based arithmetic fluency assessment reveals developments in math cognition and math achievement from childhood to adolescence. npj Science of Learning. https://doi.org/10.1038/s41539-025-00314-5

q3 · i? · associational · r2

Interaction effect from the same linear-mixed effects model of RPM. The article reports a "significant interaction between problem size and operation" with partial R2 = 0.007, in which the problem-size slope was slightly greater for subtraction problems; partial R2 from regression is not treated as an effect size.

"a subtle, yet, significant interaction between problem size and operation (R2partial = 0.007, t(10,800) = 9.90,padj < 0.001), suggesting that the slope of the problem size effect was slightly greater for subtraction problems."

Discussion¶

Related Claims¶

• Trial-level analysis replicates discrete-trials effects: fluency decreases with problem size, is faster for addition than subtraction, and increases across grade — related