Final answer:
The amount of time devoted to studying is causally related to GPA, with study time being twice as important as combined SAT scores or class attendance in determining GPA.
Step-by-step explanation:
The factor that is causally related to deciding how much time to devote to studying is the relationship between the number of hours spent studying and academic performance outcomes such as GPA. An equation indicating that GPA depends on three factors: combined SAT score, class attendance, and the number of hours spent studying, illustrates this point. Specifically, the equation highlights that study time contributes twice as much to the GPA compared to the other two factors.
Given that combined SAT score is fixed after taking the test, a student can improve their GPA more effectively by ensuring good class attendance and increasing the amount of time devoted to studying. Data showing that 70% of students study seven or more hours per week implies that dedicating a substantial amount of time to studying is a common practice that may correlate with better academic performance.