I read that IQ was originally designed to predict
success in school.
I don't believe everything I read.
There's a big difference between "originally designed
to predict" and "actually successful at predicting".
It is relatively straightforward to test what a
person knows at the moment; it is much, much harder
to predict what a person will achieve later.
I haven't found anybody seriously claiming to make such
predictions ... and if I do find them, I will assume
they are charlatans until proven otherwise.
Furthermore, even a moment's thought reveals that
intelligence is multi-dimensional -- therefore any
one-dimensional number like an IQ value cannot possibly
represent intelligence. There's a theorem that says
you cannot change dimensionality in a way that is one-to-one
and continuous.
The College Board has repeatedly redefined what SAT
stands for; currently it is "Scholastic Assessment
Test"... but it doesn't say precisely what it is
assessing.
Similar remarks apply to the GREs. There's a much
longer list of what they don't predict than what
they do.
] The Graduate Record Examination (GRE)
] does little to predict who will do well in graduate school for
] psychology and quite likely in other fields as well, according to a
] new study by Cornell and Yale universities.
]
] Of the three subtests of the GRE (verbal, quantitative and
] analytical) and the GRE advanced test in psychology, only the
] analytical subtest predicted any aspect of graduate success
] beyond the first-year grade point average (GPA), and this
] prediction held for men only. The verbal subtest and psychology
] test predicted first-year GPA, but this prediction vanished by the
] second year's GPA.