I am inclined to believe that if a student takes one of those classes to gain a better chance to receive 100 extra points is biased. I think that...

 I am inclined to believe that if a student takes one of those classes to gain a better chance to receive 100 extra points is biased. I think that organizations such as Kaplan, Princeton Review, etc., sell this notion as a marketing strategy to gain more attraction to their programs. Now, I'm sure that they may have excellent teaching and learning strategies for students to raise their scores on the SAT. But, how do we know if they are teaching the test in some way or the another? Also, with so many YouTube tutorials, SAT labs, etc., out there that help with various subjects - a virtual classroom I learn from all the time - how do we know for sure that a student can't yield a higher score from watching a video lecture regarding the various subjects under the SAT? So, there are a lot of variables (i.e., type of learner, case studies) to consider when organizations make these types of claims.

please disscuss on the idea.