A researcher is interested in looking at the effect of sleep and caffeine on physical performance. The researcher has each subject perform a series of 6 tests across a number of week. The researcher alters the amount of sleep the subject should receive (8 hours, 6 hours, and 4 hours) while also altering whether they drink coffee in the morning or they do not. These two factors are completely crossed to create the six conditions. Eight subjects were recruited for the study and performed a physical test in a lab. Higher scores on the test indicate better performance.