The reviewer reports that Baldwin's repeated examinations show the IQ is fairly constant though subject to fluctuations, and that repeated examinations exhibit a definite practice effect¶

Claim · All claims
Evidence · 1 study (2 entries) · review r? · q2
Currency · newest study 1922 · 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.

q2 i? Baldwin's data show the IQ is fairly constant though subject to fluctuations, so far as the measurements made are reliable. → Sandiford 1922 q2 i? The results of repeated examinations exhibit a definite practice effect. → Sandiford 1922 (2)

Evidence¶

Sandiford 1922¶

Sandiford, P., & R. P. (1922). New Publications: reviews of Baldwin's mental growth study, Root's A Socio-Psychological Study of 53 Supernormal Children, and Ballard's Group Tests of Intelligence. The Journal of Educational Psychology. https://psycnet.apa.org/journal/edu

q2 · i? · review · r?

Sandiford's review of Baldwin's mental growth work reports this as Baldwin's finding on the constancy of the IQ; the review states Baldwin "shows conclusively that it is fairly constant though subject to fluctuations."

"He shows conclusively that it is fairly constant though subject to fluctuations so far as the measurements made are reliable."

Sandiford 1922 (2)¶

q2 · i? · review · r?

The same review attributes to Baldwin the finding that repeated examinations show a practice effect; no effect size or test statistic is printed in the review.

"He has also pointed out that the results of repeated examinations exhibit a definite practice effect."

Discussion¶

IQ is only approximately constant across successive examinations, with first-to-fifth IQ correlation of +0.82 and prediction error of 4 to 7 points — a narrower finding that bears on this claim
IQs obtained by dividing mental by chronological age remain fairly constant up to the age of 14, which supports treating yearly increments of intelligence as equal absolute units up to about age 14. — a narrower finding that bears on this claim
The reviewer judges Goddard's book an optimistic, clear popular account that exaggerates intelligence's influence and omits technical questions such as IQ validity — related
Cephalic index computed from calliper head measurements shows fluctuations in both children, with parental indices of 78.8 and 81.8 — related

Page metadata

Field	Value
`type`	`claim`
`id`	`iq-fairly-constant-with-fluctuations-and-practice-effect`
`title`	`The reviewer reports that Baldwin's repeated examinations show the IQ is fairly constant though subject to fluctuations, and that repeated examinations exhibit a definite practice effect`
`description`	`The reviewer reports that Baldwin's repeated examinations show the IQ is fairly constant though subject to fluctuations, and that repeated examinations exhibit a definite practice effect`
`status`	`review`
`evidence_strength`	`weak`
`newest_evidence`	`1922`
`generated`	by `process:wiki-ingest` on `2026-10-24`
`trust`	unverified — no one has confirmed this page's content
`sources`	2 — `sandiford-1922`, `sandiford-1922-2`

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