Spearman’s hypothesis tested in Yemen on the items of the standard progressive matrices plus : a reply to Díaz, Sellami, Infanzón, Lanzón, and lynn (2012)‎

Abstract EN

Spearman’s hypothesis simply states that differences between groups on an IQ test are a function of the general intelligence (g).

At the item level this would mean the magnitude of the differences between groups are smaller on low-g-loading items and larger on items with a high g loading.

An empirical test by Díaz, Sellami, Infanzón, Lanzón, & Lynn (2012) comparing Spanish and Moroccans taking the Raven’s Progressive Matrices showed no support for Spearman’s hypothesis, whereas other empirical studies showed modest to strong support.

In the present study we tested whether another sample from the Arab world would replicate the outcomes of Díaz et al.

of no support for Spearman’s hypothesis by computing a correlation between g loadings and group differences on items of an IQ tests and checking whether it showed a negative correlation.

Children from Yemen (total N = 1916) were compared with a group of Russian children (N = 426) and a group of Kazakh children (N = 656) on the Standard Progressive Matrices Plus yielding outcomes of Spearman’s hypothesis of, respectively, r = .86 (p < .0005), and r = .76 (p < .0005).

The Nharmonic-weighted average correlation of .80 has a credibility interval ranging from .74 to .86.

Based on the results we conclude that Spearman’s hypothesis holds even at the item level and that the Díaz et al.

study appears to be an outlier.