* Country: SAT prep courses are far more prevalent in the United States than in other countries. In countries where other standardized tests are dominant (e.g., the UK with A-Levels), the percentage would be much lower.
* Socioeconomic status: Students from higher socioeconomic backgrounds are far more likely to have access to and afford SAT prep courses.
* High school type: Students attending private schools or those with extensive college counseling resources are more likely to participate in prep courses than students at public schools with limited resources.
* College aspirations: Students aiming for highly selective colleges are more likely to take prep courses than students with less ambitious college plans.
While various studies and surveys exist on test preparation, they usually focus on specific demographics or regions, making it impossible to give a single, accurate global percentage. It's safe to say that a significant portion of students aiming for competitive colleges in the US take some form of SAT prep, but pinning down a specific percentage is unreliable.