Ms. Peterson studied her students' history test scores and sleeping habits. She found that students who slept less tended to earn lower scores on the test. What conclusion should she make?
There is no correlation between test score and amount of sleep.
There is a correlation between test score and amount of sleep. There is probably also causation. This is because
there is a decrease in a student's test score with a decrease in the amount of sleep.
There is a correlation between test score and amount of sleep. There may or may not be causation. Further studies
would have to be done to determine this.