The Cattell-Horn-Carroll (CHC) or three-stratum model of intelligence envisions human intelligence as a hierarchy. General intelligence (g) is situated at the top, under which are a group of broad intelligences such as verbal, visuospatial processing, and quantitative knowledge that pertain to more specific areas of reasoning. Some broad…

Researchers often include covariates when they analyze the results of randomized controlled trials (RCTs), valuing the increased precision of the estimates over the potential of inducing small-sample bias when doing so. In this paper, we develop a sufficient condition which ensures that the inclusion of covariates does not induce small-sample bias…

A meta-analysis of 22 studies evaluating the relation of different assessments of IQ and intervention response did not support the hypothesis that IQ is an important predictor of response to instruction. We found an R[superscript 2] of 0.03 in models with IQ and the autoregressor as predictors and a unique lower estimated R[superscript 2] of 0.006…

This article finds the empirical review of the intellectual effects of family factors by Lala Carr Steelman wanting because (1) it is selective and incomplete; (2) it ignores systematic aggregate effects; (3) it imposes linear analysis on nonmonotone relationships; and (4) it disregards most of the confounds identified by Steelman as crucial.…

The author responds to criticism by R. B. Zajonc on a review of the extant literature on the intellectual consequences of sibship size and birth order. (Author/LMO)