The dataset Exp1 contains data from a hypothetical study of 25college students who participated in a "brain training" program in which they had to complete puzzle challenges through a smartphone app every day during a semester. We measured their GPA for the semester before starting the program ("GPASemester1") and at the end of the semester in which they used the program ("GPASemester2"). The variable GPAImprove gives the difference between these two GPAs (positive values indicate an increase in GPA after using the program