All studies with randomized controlled experiments (scientific studies) on the effectiveness of SAT test preparation courses were analyzed to find SAT prep's true effectiveness (the average point change to average course hours ratio). The scientific studies complete with both known average point change and known average course length (complete scientific studies) revealed a ratio of +3.29 points per hour with the independent complete scientific studies yielding +6.42 points per hour and the College Board/ETS complete scientific studies yielding +2.84 points per hour. Next, a regression analysis was performed on each data set in order to gauge the strength of the course hours variable at predicting point change outcomes across studies with substantively different treatments. The independent complete scientific studies yielded the largest regression correlation (78.37%) and the most recommendable and practical equation found by the present study (5.04x + 10.5 = y). The historical context was then analyzed and reconciled with the above findings.