Identifying Assumptions in Study Performance

Dr. Smith is conducting a study to determine whether students who study late into the night perform better on exams than those who study during the day. While preliminary results suggest that night-time studiers scored higher, Dr. Smith believes that a student's natural ability to retain information also plays a significant role in exam performance. Therefore, she concludes that for her study to be valid, it must show that the time of study is the only factor affecting exam scores.