Final answer:
A lurking variable in the observational study on binge drinking and GPA could be stress levels, which might lead to both increased drinking and lower academic performance. Other factors such as class attendance and hours spent studying are also important, as they are directly related to GPA and may be affected by binge drinking.
Step-by-step explanation:
In an observational study, it was found that students who engage in binge drinking have a lower average GPA than those who don't. A potential lurking variable that could be confounded with the effects of binge drinking on GPA is stress level. High stress levels may lead both to increased binge drinking as a coping mechanism and to lower academic performance due to its negative impact on concentration and mental health. Confounding occurs when the lurking variable, such as stress, affects both the independent variable (binge drinking) and the dependent variable (GPA), making it difficult to establish a direct causal link between binge drinking and lower GPA.
Additionally, factors such as class attendance and hours spent studying could also be lurking variables. For example, binge drinking could lead to missing classes or studying less, both of which are directly associated with lower GPAs. The formula GPA = 0.25 x combined_SAT + 0.25 × class_attendance + 0.50 × hours_spent_studying illustrates that class attendance and study time are significant contributors to GPA, highlighting how binge drinking might indirectly affect GPA through these factors.