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¶

Claim · All claims
Evidence · 1 study · associational r1 · q2
Currency · newest study 1921 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? Retested mental defectives as a group did not deteriorate in IQ; the average change was an increase of +1.28 points, with a standard deviation of 5.83 and the middle 50 per cent between -3.3 and +4.8. → 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 · r1

Retest study of 126 unselected inmates of Children's Hospital, Randall's Island, excluding epileptics, with intervals from six months to three years. The article reports "The average change is an increase of + 1.28" and a standard deviation of 5.83; no effect size is printed.

"The average change is an increase of + 1.28. The middle 50 per cent lie between — 3.3 and -j- 4.8 variation. The Standard Deviation was found to be 5.83."

Discussion¶

Related Claims¶

• 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 — 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