Lynn (2010) suggests that differences in average intelligence explain many of the differences observed across the Italian regions. This paper puts forward a methodological critique to his study, coupling it with an empirical test showing that Lynn's analysis is not sufficiently robust to support its conclusions. (Contains 2 tables.)

Beraldo (2010) and Cornoldi, Belacchi, Giofre, Martini, and Tressoldi (2010) (CBGMT) have eight criticisms of my paper (Lynn, 2010) claiming that the large north-south differences in per capita income in Italy are attributable to differences in the average levels of intelligence in the populations. CBGMT give results for seven data sets for IQs in…

Working with data from the PISA study (OECD, 2007), Lynn (2010) has argued that individuals from South Italy average an IQ approximately 10 points lower than individuals from North Italy, and has gone on to put forward a series of conclusions on the relationship between average IQ, latitude, average stature, income, etc. The present paper…

Recent studies are examined for methodological adequacy in establishing dimensions of individual differences in information-processing abilities, and the theoretical problems involved in inferring psychological processes from individual difference dimensions. Methodological inadequacies include use of small samples, questionable procedures in…

A reply to Plomin's critique and some criticisms of Munsinger's review of adopted child literature are presented. Selective bias in adoptee samples, implicit assumptions in models that lead to heritability estimates, and problems produced by lack of an accepted model of environmental transmission are also discussed. (Author/RD)

The author refutes Humphrey's test of the Spearman hypothesis. A fair test requires that Black and White samples not be selected on any g-correlated variable, including socioeconomic status. Humphrey's factor analysis on test-score means of demographic groups, rather than on individuals, inflates g loadings and biases results. (LMO)

This author reviews published data and presents new data relevant to the Spearman hypothesis concerning racial differences on cognitive tests. He concludes that across-the-board difference between SES groups occurs primarily on the general factor, and that there are major determinants of race differences independent of the general factor.…

The author responds to criticisms made by Jensen pertaining to tests of the Spearman hypothesis. The near-zero correlation between Blacks and low socio-economic status Whites is neither an artifact of methodology nor a sampling fluke. Low and high SES White differences are highly correlated with general factor loadings. (LMO)