Test preparation does not do much to increase SAT scores:
"For students that have taken the test before and would like to boost their scores, coaching
seems to help, but by a rather small amount. After controlling for group differences, the
average coaching boost on the math section of the SAT is 14 to 15 points. The boost is
smaller on the verbal section of the test, just 6 to 8 points. The combined effect of
coaching on the SAT for the NELS sample is about 20 points."
I went through the Princeton Review many years ago and it improved my score by about 200 points.
Maybe I'm an outlier, but I can tell you this: nobody would pay for or go through the course if the expected boost was 20 points.
On the other hand, if I hadn't taken the Princeton Review, I'd have done something else to prep. And who knows how much I'd have been able to improve on my own.
They did not measured whether it is possible to prepare for SAT. They measured whether commercial courses boost your score. The comparison is not between student who does no additional work for SAT and the one who study a lot. The comparison is between student enrolled paying coach and the one who is not paying special SAT coach. The latter one can still work a lot with help of books and websites.
It does not mean you can not prepare for SAT, it just means that money spent on commercial coach are probably wasted. It says nowhere that if you skip all preparation altogether, you will get good result.
Quote: "Most studies have focused on estimating the effect of one specific type of test preparation, known as “coaching.” In this analysis, students Students have been coached if they have enrolled in a commercial preparation course not offered by their school but designed specifically for the SAT or ACT. The distinction made here is whether a test-taker has received systematic instruction over a short period of time. Preparation with books, videos and computers is excluded from the coaching definition because while the instruction may be systematic, it has no time constraint. Preparation with a tutor is excluded because while it may have a time constraint, it is difficult to tell if the instruction has been systematic."
Article conclusion focus on coached students only.
Note the time constraint in the above quote. People who take those tests seriously not only take the short course, but probably focused on the test long before the course started. At least, that is how well performing students I knew years ago behaved. The course itself might have boost their score only a little, but their preparation consisted of much more then just one course. After all, they are adults about to enter college - they are expected to be able to learn alone.
Most coaching is really poor. I used to do math prep for the SAT and I consistently improved scores more than the data would predict. After sitting through Princeton Review, it was easy to see why.
I suspect those that benefit the most from prep aren't telling.
"For students that have taken the test before and would like to boost their scores, coaching seems to help, but by a rather small amount. After controlling for group differences, the average coaching boost on the math section of the SAT is 14 to 15 points. The boost is smaller on the verbal section of the test, just 6 to 8 points. The combined effect of coaching on the SAT for the NELS sample is about 20 points."
http://nepc.colorado.edu/files/Briggs_Theeffectofadmissionst...