The distribution of IQ changes among mental defectives does not differ from Terman's curve for unselected school children, indicating mental defectives are not more variable than normal subjects¶

Claim · All claims
Evidence · 1 study · associational r2 · q2
Currency · newest study 1921 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? The retest change distribution for mental defectives does not differ from the curve Terman worked out from unselected school children, suggesting mental defectives are not more variable than normal subjects. → Poull 1921

Evidence¶

Poull 1921¶

Poull, L. E. (1921). Constancy of the I.Q. in mental defectives according to the Stanford revision of Binet tests. Journal of Educational Psychology, 12(6), 323–324. https://doi.org/10.1037/h0071851

q2 · i? · associational · r2

Visual inspection comparison of the retest change distribution from the 126-case institutional sample against Terman's published curve for unselected school children; the article reports the curves "does not differ" but prints no statistical test or effect size.

"It is significant that the curve does not differ from the one worked out by Terman from the records of unselected school children."

Discussion¶

Related Claims¶

• On retest, institutionalized mental defectives as a group show no IQ deterioration, with a mean change of +1.28 points and a standard deviation of 5.83 — related
• A large percentage of retested cases show IQ variations large enough to change their classification, demonstrating the injustice of disposing of persons on the basis of a single test — related