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¶

Claim · All claims
Evidence · 1 study (2 entries) · qualitative r2 · q1
Currency · newest study 1922 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q1 i? Case analysis shows that large IQ differences often have a reasonable basis, including failure of previously passed tests, chance success on single high-credit tests, and failure to put forth full effort. → Lincoln 1922 q1 i? Case 24's lower first IQs were attributed to the subject's failure to put forth full effort during testing. → Lincoln 1922 (2)

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

q1 · i? · qualitative · r2

Qualitative case analysis of Number 3's four successive Stanford-Binet records. The 1920 slump is explained by "he failed three tests which he had passed the previous year," and passing those would have raised his IQ from 94 to 101.

"In this test he failed three tests which he had passed the previous year, and he was not given the chance to make points on the form board as previously."

Lincoln 1922 (2)¶

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

q1 · i? · qualitative · r2

Case analysis of Number 24, whose first IQ of 114 with wide scatter and a Doll Short Test IQ of 125 contrasted with later scores of 112 and 124. The author writes "It seems reasonable to suppose that the lower IQ's resulting from the first examinations were due to the failure of the subject to put forth his full effort during the testing."

"It seems reasonable to suppose that the lower IQ's resulting from the first examinations were due to the failure of the subject to put forth his full effort during the testing."

Discussion¶

Related Claims¶

• Repeated Stanford-Binet testing of summer-school pupils over four years shows mostly small IQ differences, with a median difference of 5.25 points — related
• 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 — related
• IQ scores tend to run low in communities where adults are engaged mostly in unskilled or semi-skilled labor, and apparent age- or grade-level anomalies usually have an explainable cause — related
• Moral factors were judged roughly four times as often as intellectual incapacity as the cause of laggards' failure — 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