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

The Heritability of Scholastic Achievement 109
pEs = correlation between school environmental influences
on persons A and B
E2p = family ‘environmentability’ (i.e., proportion of test
score variance attributable to environmental differences
among families)
E2S = school ‘environmentability’ (i.e., proportion of test
score variance attributable to variability in schooling).
If the paired individuals are genetically unrelated, and were not
reared in the same family, and have not attended the same classes
in school (or the same or similar schools), then pG, pEe, and pEs
will all be zero and rAB will be zero. Values of rAB greater than zero
can be due to any combination of the values of the several components
given in the above formula.
If now we have obtained sibling correlations (rs) in two subpopulations,
1 and 2, and if we assume that (a) the genetic correlation
of siblings is the same in both subpopulations, (b) the
heritability (h2) is the same in both groups, and (c) the school
influences are the same for both subpopulations, then the difference
between the sibling correlations in the two subpopulations should
be an estimate of their difference in proportion of test variance
attributable to the (between) family environmental effects, i.e.,
r sl ~ r S2= :(rEF l^ F l ~ P E F 2^ F 2
The value PepEv, of course, tells us nothing about the quality or
direction (poor v. good) of the family environmental influences. It
merely estimates the proportion of sib correlation attributable to
this source. And rst —rSi estimates how much two subpopulations
differ in pEf.Ej, i-e., family environmental influences on scholastic
achievement.
I have obtained sibling correlations (intraclass riy using all the
school-age siblings in each family) on large samples of white and
Negro children in a California school district. The sample sizes
on which the sibling correlations are based represent virtually all
the siblings in the elementary school district (fourteen schools)
who had taken either the same tests or sufficiently similar tests to
permit intercorrelation.
All of the tests were administered by a staff of specially trained
testers in order to maximize uniformity of testing procedures. The
raw test scores (as well as measures of height and weight) were
converted to normalized standard scores within each 6-month age