Educability-and-Group-Differences-1973-by-Arthur-Robert-Jensen

Accentuated Environmental Inequalities 251
of the g factor of intelligence, the Mexicans were intermediate
between whites and Negroes, as shown in Figure 12.1, despite
the lower SES and poorer motivation of the Mexican pupils.
Finally, a factor analysis was performed on the intercorrelations
among all the variables in all three ethnic groups combined. Four
major factors emerged: (I) scholastic achievement and verbal
intelligence, (II) non-verbal intelligence, (III) rote memory ability,
Verbal IQ & N on-verbal IQ Mem ory Socioachievem
ent (ro te ) econom ic
status
Figure 12.2 Factor scores (mean = 50, SD = 10 within each
grade level) for four variables, comparing white, Mexican-American
and Negro samples in grades 4, 5 and 6. The factor scores are
independent of one another; that is, the scores on any one factor
reveal differences between subjects who are statistically equated on
the three other factors. (From Jensen, 1971a, Table 6.)
(IV) socioeconomic status. Minor factors were (1) speed, motivation,
and persistence, (2) neuroticism, (3) extraversion, (4) age in
months. These variables are, in effect, partialled out of the major
factors. Since the four major factors are orthogonal (i.e., uncorrelated
with one another) by virtue of the type of factor analysis
used (varimax rotation of the principal components), each one
can be viewed as a ‘pure’ measure of a particular factor in the sense
that the influences of all the other factors are held constant. Factor
scores were obtained for every pupil on each of the four main
factors. (The factor scores have an overall mean of 50 and a
standard deviation of 10.) The mean factor scores of the three