Question

In its January 25, 2012, issue, the Journal of the American Medical Association (JAMA) reported on the effects of overconsumption of low, normal, and high protein diets on weight gain, energy expenditure, and body composition. Researchers conducted a single-blind, randomized controlled trial of 25 U.S. adults. All subjects were admitted to the inpatient metabolic unit for the duration of the trial (10 to 12 weeks). The subjects were healthy, weight-stable, male and female volunteers, aged 18 to 35 years. All subjects consumed a weight-stabilizing diet for 13 to 25 days. Afterward, the researchers randomly assigned participants to diets containing various percentages of energy from protein: 5% (low protein), 15% (normal protein), or 25% (high protein). The subjects were not aware of the specific protein level diet to which they were assigned. On these diets, the researchers overfed the participants during the last 8 weeks of their 10 to 12-week stay in the inpatient metabolic unit. Which of the following is used in the design of this experiment? Check all that apply. Group of answer choices Control group Blinding of subjects Blinding of researchers. Direct control of confounding variables Random assignment

Answer 1

The same group of individuals were given usual diet and then overfed. thus, we do not have a separate control group. the same group was used to draw the two kind of responses. Hence we got paired observations and there are no Cnontrol groups.

The sujects didn't know about their diet, so Blinding of Subjects occurred.

It's not mentioned that the researchers were blinded. Though they did randomised the diets, but we will assume, in absence of a mention, that the researchers knew who got which diet. Thus, Blinding of Researchers didn't occur.

We don't have any mention of confounding variables or any measure to control that. Thus, Direct control of confounding variables didn't occur.

It's mentioned that the diets were assigned randomly. Hence, random assignment occurred.

Thus the following occurred in the experiment: Blinding of Subjects, Random Assignment.