Chapter 11, Problem 45E

Hamstrings Exercise 33 discussed an experiment to see if the time it took athletes with hamstring injuries to be able to return to sports was different depending on which of two exercise programs they engaged in.

1. a) Explain why it was important to assign the athletes to the two different treatments randomly.
2. b) There was no control group consisting of athletes who did not participate in a special exercise program. Explain the advantage of including such a group.
3. c) How might blinding have been used?
4. d) One group returned to sports activity in a mean of 37.4 days (SD = 27.6 days) and the other in a mean of 22.2 days (SD = 8.3 days). Do you think this difference is statistically significant? Explain.