Here is another multiple choice problem:
A new dietary supplement was given to a volunteer group of 25 people who were at least 50 pounds overweight. 18 people from the group lost at least 20 pounds. What can we conclude about the effectiveness of the diet?
A) The diet was effective in 72% of the cases
B) The mean wight loss was more than 20 pounds
C) Nothing since 25 people were not an SRS
D) Nothing since there were no control group that reieved a placebo
E) Nothing since the group knew they were usind the diet
I think that D) is the right answer. Can you help me?