My daughter recently got her SAT scores back. She did far better on the math and verbal skills portions than on the essay portion of the test.
I remember feeling disgruntled when I first heard years ago that they were going to include an essay portion on the SAT. Up until then the beauty of the test had been that it was a rigorously objective test, a reliable standardized counterpoint to the grades that students receive in high school.
Those grades are a far squishier measure of intellectual aptitude than the SATs, and are reflective of all sorts of behaviors which simply don't reflect cognitive ability. For instance, did you display a properly respectful attitude in class? Did you butter up the teacher? Did the teacher like you? What sort of curve did the teacher grade on? Did you have good study partners? Did you cheat on the test and get away with it? Did you use other people's material for your term paper?
The SAT allowed for none of those factors, and was graded by machines. But now, with the essay, that is no longer entirely true. Your essay is now graded by a human, with all of the attendant error and bias. Was your essay the first he graded that day, or the last, and how did that affect the grade he assigned? Did he read it carefully, or was he tired when he read it? Did he object to your political point of view? All of those factors can feed into the score he gave you.
As a result, SAT results are no longer quite the objective measure they once were.
I know I sound like a disgruntled father, but I have felt this way since long before last week. Anytime you inject a fudge factor into a previously pure process, you corrupt it.
It's a little like saying that the outcome of running races will no longer be determined just by the stopwatch, but also partially by a group of judges who score the runners on their form.