Math

the south beach diet was given to a volunteer group of 25 people who were at least 50 pounds overweight. eighteen people from the group lost at least 20 pounds. what should we conclude about the effectiveness of the diet?
. nothing since the group knew they were using the diet
. the diet is effective in 72% of people
. nothing since the 25 people were not an srs
. nothing since there was no control group
. people overweight by at least 50 pounds will lost more than 20 pounds on the diet

a group of 8 people work on the fifth floor of the peyton building. they all decide they want to lose weight by getting more exercise. 4 of them decide to walk up the four fliughts of stairs each morning. the other four walk down the four flights of stairs at the end of the day. they weight themselves each friday morning and compare. this is an example of
. an observational study, since they were not assigned groups
. an experiment, since they are randomly divided into two equal groups
. block design, since there are two treatments
. a survey since the people volunteered to measure weight each week
. an explanatory variable since they both increase their exercise