A group of researchers wants to study the effect of listening to music at different volumes on driving reaction times. They recruit 100 volunteers. They assign each subject a number from 1 to 100 and use a random number generator to assign the first 50 subjects selected to take the driving test with one music volume. The remaining 50 subjects are assigned to take the test with the second music volume. What type of experiment design is this?
1) systematic
2) completely randomized
3) cluster
4) randomized block
5) matched pairs
