An investigator randomly assigns 30 college students into three equal size study groups (early morning, afternoon, late-night) to determine if the period of the day at which people study has an effect on their retention of predetermined study material. In computing the ANOVA table, the researcher finds that the MS within groups is larger than the MS between groups. What does this result indicate? That the three group means came from three populations with different means O There should have been a control group in the experiment That the three group means likely came from a single population O There was more than the expected amount of variability between groups