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

2 Current technical misconceptions
and obfuscations
Readers who have kept up with the current literature in this field
are apt to have encountered a number of issues which have created
confusion. It will pay to clear up these misconceptions so they will
not interfere with the understanding of the more fundamental
problems to be discussed in the remainder of this book.
POPULATION V. INDIVIDUAL
One current misconception concerns the meaning of heritability
(henceforth signified by h2) in relation to individual measurements
or test scores.* The fact that h2 is derived from the concepts and
methods of the branch of genetics called quantitative genetics and
depends upon population samples for its estimation has led some
writers to believe, or at least to create the impression, that h2 has
no relevance to individual scores. And there are some persons who
apparently find some comfort in the notion that even though
the estimation of h2 might have some validity with respect
to a population, it has no relevance to the individual. An
implicit extension of this line of reasoning is that since h2 is
irrelevant for the individual and since populations are composed
of individuals, h2 must really not mean anything in populations
either.
The fact is, h2 pertains both to individual scores and to population
variance. What it does not pertain to is the population mean.
* See Appendix on Heritability for an explanation of how h2 values are
empirically obtained.