Question

1. A nutritionist wants to conduct a study to validate the effectiveness of a certain herb as an aid in weight loss. She has her nurse randomly assign half a group of overweight people to receive the herb with instructions on how to take and a planned diet for six weeks. The other half of the group is given parsley (which they think is the herb) with the same instructions and the same diet. Each participant is assigned a number and the nurse weighs each subject on Friday of each week. Upon completion of the six weeks she gives the nutritionist the weights of each subject by their assigned number.

1. Is this a single blind or double blind experiment?

2. What is the treatment?

3. What is the placebo?

4. Describe the type of data that this experiment will generate

Answer 1

(a) This is a double blind experiment.

Reason: Neither the participants nor the researcher (here, the nutritionist) is aware who is receiving treatment or placebo, because it is known only to the nurse.

(b) The treatment is eating the herb with a planned diet

(c) The placebo is eating parsley (which the participants think is the herb) with the same diet

(d) The data that this experiment will generate is the decrease in weight of all the participants of both groups.