An online article in 2001 described a study in which twelve sixth-grade students who had not previously played chess participated in a program where they took chess lessons and played chess daily for 9 months. Each student took a memory test (the Test of Cognitive Skills) before starting the chess program and again at the end of the 9 month period. Data and computed differences are given in the accompanying table. The author of the article proposed using these data to test the theory that students who participated in the chess program tend to achieve higher memory scores after completion of the program.