21.   Some patients who want an experimental procedure might be assigned instead to a comparison group that received the best standard care.

22.   The final group of participants was randomly assigned to either the intervention group or a comparison group that was given only a booklet on healthful eating.

23.   The researchers wrote that they had expected that a lot of the children in the comparison group would leave.

24.   These studies cannot be used to demonstrate whether the procedure is any better than the standard treatment, because there is no comparison group of similar patients.

25.   They found that the men gained muscle, lost fat and developed thicker skin, while a comparison group did not.

26.   Those who took the glycine showed a marked improvement in negative symptoms, while a comparison group taking a placebo showed no improvement.

27.   Overall, the wheat grown near Chernobyl mutated at more than six times the rate of the comparison group.

28.   A comparison group inhaled a dummy solution.

29.   A comparison group received dummy placeboes.

30.   All of the mice in comparison groups that received an ineffective antibody developed lung tumors.