Repeated Stanford-Binet testing of summer-school pupils over four years shows mostly small IQ differences, with a median difference of 5.25 points¶

Claim · All claims
Evidence · 1 study · associational r1 · q2
Currency · newest study 1922 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q2 i? When each IQ of an individual was compared with all other IQs of the same individual across four years of testing, the median difference was 5.25 points and the upper quartile 11.5. → Lincoln 1922

Evidence¶

Lincoln 1922¶

Lincoln, Edward A. (1922). The Constancy of Intelligence Quotients (A Case Study). The Journal of Educational Psychology, 14, 484-495. https://archive.org/details/journalofeducat14

q2 · i? · associational · r1

Analysis of repeated Stanford-Binet examinations of summer-school pupils from 1918 to 1921, comparing each IQ with all others for the same child. The printed distribution shows "The median of these differences is 5.25 points and 11.5 is the upper quartile," with three-quarters of differences described as not significantly large.

"The median of these differences is 5.25 points and 11.5 is the upper quartile. Thus it seems that three-quarters of the differences are not significantly large"

Discussion¶

Related Claims¶

• Large IQ differences in this sample were mostly attributable to identifiable causes such as failures of previously passed tests, chance success, effort fluctuation, or lack of experience — related
• 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. — related
• 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 — related
• The question of the constancy of IQ is not settled; further studies with regular intervals and repeated tests of the same cases over a number of years are needed — related