Question: A study is conducted to determine if time of day has any effect on test grades. An introductory psychology class is selected for the study, because it has a standard curriculum taught across many sections. Two classes are selected for each time period: 8:00 AM, 1:00 PM, and 5:30 PM. Out of the total pool of around 40 students for each time period, 15 students are selected at random, for a total of 45. The test is administered to all students, and the test results for the study subjects are placed in SPSS. We want to know if there is a statistical difference between these time periods. What test is appropriate?