The present article provides a primer on using effect sizes in research. A small heuristic data set is used in order to make the discussion concrete. Additionally, various admonitions for best practice in reporting and interpreting effect sizes are presented. Among these is the admonition to not use Cohen's benchmarks for "small," "medium," and…

This paper examines the distribution of national IQ in geographical space. When the heritability of IQ and its dependence on eco-social factors are considered from a global perspective, they suggest that the IQs of neighboring countries should be similar. Using previously published IQ data for 113 nations (Lynn, R., & Vanhanen, T., (2006). IQ and…

Presents arguments for the case that Burt did fake his results. (IRT)

Argues that Burt did not fake his results. (IRT)

Comments on some methodological limitations of the research base of "The Bell Curve": blind use of the normal distribution (bell curve); avoidance of nonnormal statistical distributions, which are more appropriate for some social and economic characteristics; copious use of percentiles and quintiles, inappropriate with nonnormal…

This study refutes the Elashoff and Snow (1970) critique of "Pygmalion in the Classroom," a study by Rosenthal and Jacobson (1968) on the effect of favorable teacher expectance on pupil achievement. Among the theses considered erroneous are: (1) That there is a wide variation in apparent results when different methods of data analysis…

Extending the classical twin method, Arthur R. Jensen claims to find unique estimates of the variance and covariance of the genetic and environmental components of IQ. The analyses presented in this paper show that a wide variety of parameter estimates are compatible with his model and data. But the extent of indeterminancy is deemed to be even…

This study bears on Arthur R. Jensen's latest statement on the heritability of intelligence. Allowing for gene-environment correlation, Jensen (1975) reports that under a wide range of assumptions, the twin data show that one-half to three-fourths of IQ variance is accounted for by genetic factors. This conclusion falls when an arbitrary…

Criticizes data analysis and interpretation in "The Bell Curve:" Herrnstein and Murray do not actually study the "cognitive elite"; do not control for education when examining effects of cognitive ability on occupational outcomes, ignore, cultural diversity within broad ethnic groups (Asian Americans, Latinos), ignore gender…