h demand on the
superior powers of the great thinker. If we could assemble a group of
the world's great authors, scientists and inventors, and put them
through the Alpha test, it is probable that they would all score high,
but not higher than the upper ten per cent, of college freshmen. Had
their IQ's been determined when they were children, {283} probably all
would have measured over 180 and some as high as 200, but the tests
would not have distinguished these great geniuses from the gifted
child who is simply one of a hundred or one of a thousand.

The Correlation of Abilities

There is no opposition between "general intelligence", as measured by
the tests, and the abilities to deal with concrete things, with
people, or with big ideas. Rather, there is a considerable degree of
correspondence. The individual who scores high in the intelligence
tests is likely, but not certain, to surpass in these respects the
individual who scores low in the tests. In technical language, there
is a "positive correlation" between general intelligence and ability
to deal with concrete things, people and big ideas, but the
correlation is not perfect.

_Correlation_ is a statistical measure of the degree of
correspondence. Suppose, for an example, we wish to find out how
closely people's weights correspond to their heights. Stand fifty
young men up in single file in order of height, the tallest in front,
the shortest behind. Then weigh each man, and shift them into the
order of their weights. If no shifting whatever were needed, the
correlation between height and weight would be perfect. Suppose the
impossible, that the shortest man was the heaviest, the tallest the
lightest, and that the whole order needed to be exactly reversed; then
we should say that the correlation was perfectly inverse or negative.
Suppose the shift from height order to weight order mixed the men
indiscriminately, so that you could not tell _anything_ from a man's
position in the height order as to what his position would be in the
weight order; then we should have "zero correlation". The actual
result, however, would be that, while the height order would be {284}
somewhat disturbed in shifting to the weight order, it would not be
entirely lost, much less reversed. That is, the correlation between
height and weight is positive but not perfect.

Statistics furnishes a number of formulae for measuring correlations,
formulae which agree in this, that perfect posi