Take 200 boys from the high school, 50 from each grade. Give 100 boys, 25 from each grade, access to the weight room whenever they would like to use it, as well as during their 3 gym classes a week. The other group was only allowed to go during their gym class, which was 3 times a week. The groups do not know that there will be a test day, in which the two groups will be measures to see which type of workout is more successful. The all-access group was blinded, as they did not know they had more opportunity to prepare for the test. The groups of boys only had one difference, the availability of the weight room. The groups were chosen randomly from the whole school system. There are plenty of subjects to provide differences in the effects of each treatment.