This from Walt Gardner's Reality Check:
The school year is finally over, but the summer will not be the idyllic time of yore for many students. Their days will be spent prepping for either the SAT or ACT, which still remain the gatekeepers for most marquee name colleges and universities.
When I was in high school, the SAT had the entire market to itself. But in 1959, the ACT was founded and slowly began to make headway. It was originally most popular in the South and the Midwest. But by 2008, the geographical distinction had largely disappeared. Nationwide that year, 1.4 million students took the ACT, while 1.5 million students took the SAT ("ACT is to SAT as ...." Los Angeles Times, Sept. 6, 2008).
Which test should students choose? Although the ACT is less expensive, its growing appeal is still unclear. There is no evidence that either test is easier or that admissions officers are more impressed with one over the other. Some students are swayed by the ACT's claim that it is an achievement test, while the SAT is seen as an aptitude test ("Scores Stagnate at High Schools," The Wall Street Journal, Aug. 18, 2010). But this belief confuses the two terms. An achievement test measures knowledge and skills; an aptitude test predicts the likelihood of success in a future setting. While the two sometimes are related, they are not the same.
To understand the reason, it's instructive to look at the changes made in the name of the SAT over the years. In 1926, Carl Brigham conceived the test as an instrument for promoting greater meritocracy. He called it the Scholastic Aptitude Test, in the belief that it assessed innate ability. But by 1994, the College Board, which owns the test, renamed it the Scholastic Assessment Test because the original designation was associated too often with eugenics. In 1997, however, the board again altered the name to simply the SAT, which stands for nothing ("UnSATisfactory," Education Week, Jun. 14, 2006).
What students and their parents need to bear in mind is that both tests are designed to engineer score spread among test takers. If the tests were loaded up with items that truly measured effective instruction, test makers would run the risk of not delivering on their promise. To avoid that possibility, both the ACT and SAT contain many items that largely measure what students bring to class in the form of their socioeconomic backgrounds. That's because such items have been shown to spread scores out.
But even more important is the role that determination and perseverance play in academic success. Neither the ACT nor the SAT measures these qualities. As a result, it's not uncommon to find students whose lackluster performance on the tests is dramatically overshadowed by their grades in college.