A clinical trial is run to assess the effects of different forms of regular exercise on HDL levels in persons between the ages of 18 and 29. Participants in the study are randomly assigned to one of three exercise groups - Weight training, Aerobic exercise or Stretching/Yoga - and instructed to follow the program for 8 weeks. Their HDL levels are measured after 8 weeks and are summarized below.
Exercise Group N Mean Std Dev
Weight Training 20 49.7 10.2
Aerobic Exercise 20 43.1 11.1
Stretching/Yoga 20 57.0 12.5
Is there a significant difference in mean HDL levels among the exercise groups? Run the test at a 5% level of significance. HINT: SSwithin = 21,860.