Category Archives: Psychometrics

A bad, invalid argument commonly used by hereditarians is the research concerning transracial adoption. The claim usually made is that black, black-white mixed-race, white, asian-white mixed-race adoptees had IQs following the well-established genetic hierarchy seemingly B < BW < W < … Continue reading →

While Rushton (1999) demonstrates, using PCA, that g and black-white differences were related, with Flynn Effect (FE) gains over time showing no relationship with the aforementioned variables, Flynn (2000) has challenged Rushton in arguing that Wechsler’s subtest loadings on the … Continue reading →

It is well known and acknowledged that IQ correlates with social outcomes (Herrnstein & Murray, 1994; Jensen, 1980, 1998; Gottfredson, 1997), measures of health (Gottfredson, 2004, & Deary, 2004; Reeve & Basalik, 2010), wages (Jones & Schneider, 2008), savings (Jones, 2012), job performance (Ree & Earles, 1994; Schmidt … Continue reading →

I discussed at length the results at Human Varieties. I will simply add some more important comments here. A lot of problems must be highlighted. Although large positive g*h2 and modest negative g*c2 correlations were found, heterogeneity of effect sizes … Continue reading →

The present analysis is an extension of Spitz’s earlier (1988) study on the relationship between mental retardation (MR) lower score and subtest heritability (h2) and g-loadings. These relationships were found to be positive. But Spitz himself haven’t tested the possibility … Continue reading →

I analyze two studies who provide the necessary data for studying the test-retest effects, namely, Watkins (2007), Schellenberg (2004, 2006). Both used the Wechsler’s subtests, and the correlations between the IQ changes among those subtests with g-loadings are negative, in … Continue reading →

The scanned version of Jensen’s book, Bias in Mental Testing, is available as a PDF. If you want my version though, email me at m h 1 9 8 7 0 4 1 0 @ g m a i l . c … Continue reading →

(Article last update : January 2015) A widely cited study (Eppig et al., 2010) has suggested that infectious disease is the most important determinant of national IQs, independently and above GDP, education and some evolutionary variables. But their analysis is … Continue reading →

Studies of the nature of the Flynn Effect are usually done in developed countries (e.g., Rushton, 1999; Wicherts, 2004; Nijenhuis, 2007; for an ‘Overview of the Flynn Effect’, see Williams, 2013). There are two recent data on two developing countries (Khaleefa, 2009; Liu, 2012). The … Continue reading →