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 criticizes these conclusions and the robustness of the data from which Lynn (2010) derived the IQ scores. In particular, on the basis of recent Italian studies and our databank, we observe that : 1) school measures should be used for deriving IQ indices only in cases where contextual variables are not crucial: there is evidence that partialling out the role of contextual variables may lead to reduction or even elimination of PISA differences; in particular, schooling effects are shown through different sets of data obtained for younger grades; 2) in the case of South Italy, the PISA data may have exaggerated the differences, since data obtained with tasks similar to the PISA tasks (MT-advanced) show smaller differences; 3) national official data, obtained by INVALSI (2009a) on large numbers of primary school children, support these conclusions, suggesting that schooling may have a critical role; 4) purer measures of IQ obtained during the standardisation of Raven's Progressive Coloured Matrices also show no significant differences in IQ between children from South and North Italy.
Lynn's feeble reply, where he's basically forced to admit he's wrong:
Beraldo (this issue) 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 the north and south of Italy. All of these show that IQs are higher in the north than in the south, although the differences are not as great as those I calculated. Other criticisms to the effect that the PISA tests are not measures of intelligence are refuted. The results of two further studies are given that confirm that IQs in the north of Italy are approximately 10 IQ points higher than in the south.
The other critique mentioned there is Sergio Beraldo (2010), which focuses mostly on Lynn's claims about economic differences.