6)
Correct option:
(B) The study is essentially free of confounding sources
Explanation:
"She randomly assigns" indicates the confounding of Method of assignment to treatment and control groups is taken care of.
The presence of control group of diet without the herb indicates that the placebo effect is taken care of.
Since "A nurse at the nutrition center weighs each subject" indicates that experimenter effect is taken care of.
0201 7) A nutritionist wants to conduct a study to validate the efficacy of an herb as an aid in weight loss She randomly assigns half of a group of overweight persons to a treatment group who...