A group of researchers wants to study the effect of listening to music at different volumes on driving reaction times. They recruit 100100100 volunteers. Half of the subjects with fewer than 101010 years of driving experience are randomly assigned to take the test with one music volume, and the other half are assigned to take the test at the other music volume. The same method is used to randomly assign half of the drivers with at least 101010 years of driving experience to each testing condition.