Direction of effect judgments for multiplication of decimals below one are more accurate when one operand is a whole number than when both operands are decimals¶
Claim · All claims
Evidence · 1 study · causalr2·q3·i2medium
Currency · newest study 2017 · not yet checked against its sources · not reviewed by a person
Subclaims¶
Reading the evidence codes
q is the design tier, i the impact, n the sample, and the kind with its r
the rigour judged within that kind: what each code means.
This claim: no standardized effect is recorded in observations/ for it yet, so no benchmark reading is possible.
q3 i2 On multiplication problems with decimals below one, judgments were more accurate on whole-number-decimal (WD) problems (M = 47%) than decimal-decimal (DD) problems (M = 31%), d = 0.41; division showed no WD advantage. → Lortie-Forgues 2017
Evidence¶
Lortie-Forgues 2017¶
Lortie-Forgues, Hugues and Siegler, Robert S (2017) Conceptual knowledge of decimal arithmetic. Journal of Educational Psychology. pp. 374-391. ISSN: 0022-0620. https://doi.org/10.1037/edu0000148
q3 · i2 · causal · r2
Study 2 judgment-only task with 54 7th graders: the operation X whole number operand X decimal size interaction was significant (F(2, 88) = 3.48, p = 0.035, ηp2 = 0.073); "direction of effect judgments were more accurate when one operand was a whole number" only for multiplication below one.
"direction of effect judgments were more accurate when one operand was a whole number (WD problems) (M = 47%, SD = 47%) than when both operand were decimals (DD problems) (M = 31%, SD = 42%) (t(53) = 2.97, p < 0.01, Cohen’s d = 0.41)."
Discussion¶
Related Claims¶
- Below Chance Direction Of Effect Decimals Below One
- No Repeated Addition Explanations Part Whole Logic
- Explanations citing both the arithmetic operation and the operands' magnitudes are strongly associated with accurate direction of effect judgments, while unconditional operation rules are associated with very low accuracy — related
- Decimal magnitude comparison accuracy is unrelated to direction of effect judgment accuracy, indicating the errors do not stem from poor access to decimal magnitudes — related
- Below-chance direction of effect judgments with decimals below one are not attributable to weak decimal computation skill — related
Page metadata
| Field | Value |
|---|---|
type |
claim |
id |
wd-multiplication-more-accurate-than-dd-decimals-below-one |
title |
Direction of effect judgments for multiplication of decimals below one are more accurate when one operand is a whole number than when both operands are decimals |
description |
Direction of effect judgments for multiplication of decimals below one are more accurate when one operand is a whole number than when both operands are decimals |
status |
review |
evidence_strength |
moderate |
newest_evidence |
2017 |
generated |
by process:wiki-ingest on 2026-10-23 |
trust |
unverified — no one has confirmed this page's content |
sources |
1 — lortie-forgues-2017 |
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