Alice wants to prove to her parents that listening to music while she does her homework will help her get better grades. She decides to ask 25 of her friends if they listen to music while they do thei

Alice wants to prove to her parents that listening to music while she does her homework will help her get better grades. She decides to ask 25 of her friends if they listen to music while they do their homework and what their grades are. She finds that her friends who have high grades also listen to music while they do their homework. She tells her parents that she has proven that listening to music while doing homework will cause her grades to improve. What mistake has Alice made?