Now, to take a moment to respond to the op-eds of those who don’t appreciate standardized tests, I want to remind people why such tests were instituted in the first instance. The exams were initiated in order to open higher education to poor kids from public schools; they were intended as a measure of academic potential that could be viewed against the subjective GPA and would not be influenced by the way the admissions officers viewed the quality of the particular school the applicant attended.
The funny thing is that SATs, which are a form of IQ test as Nephorm stated, are actually quite good at predicting purely academic success. If you look through the rolls of your National Merit Scholars or high SAT scorers (or even just kids with high IQ scores from elementary school), you will find a very large correlation of those high scores to academic success.
Does a high score guarantee success? Of course not. As has been pointed out, there are a whole slew of other factors that contribute, including the tendency to work hard (somewhat captured by GPA) and the difficulty level of material already mastered (captured by the “reputation” of the school attended and, somewhat, by studying the transcripts of the individual).
That said, I think it is a huge mistake to make the SAT more subjective by adding the essay. The admissions process is already supposed to capture that subjective side through the GPA, the transcript, and, of course, from teh essays written for the application itself. The SAT is merely supposed to be an objective measure of academic POTENTIAL (note: NOT guaranteed success), which it does somewhat well, and did much better before they started dumbing it down by allowing calculators, removing the antonym section, removing the analogies, and now, adding an essay.
(BTW, as a side note, most IQ psychologists believe that the analogies are the part of an IQ test most directly correlated to the mythical “g” or, general intelligence quotient." Those of you who want admission to graduate school will note that the GRE has not changed with the political winds as has the SAT, and has retained the form of the old SAT exam before the dumbing-down process, plus an extra section on logic (making it even more like an IQ test)).
In other words, the bottom line is that by making the SAT more subjective, they are removing the only objective measure that is available in the admissions process. That, to me, is a bad thing.