Question

over a 4-month period, among 100 people with a psychological disorder, patients who were given a high dose (877 mg/day) of a certain dietary supplement improved more than those given a placebo. the researchers kept track of and were aware of the dosages of supplements and placebos. complete parts a through h.
a) identify whether the above research is an observational study or an experiment.
the described research is an experiment

b) identify the subjects studied.
a. the subjects are psychological disorders.
b. the subjects are 100 people with a psychological disorder.
c. the subjects are the population of people with a psychological disorder.
d. the subjects are certain dietary supplements.
c) identify the factor(s) in the experiment, and the number of levels for each.
how many factors are involved in this experiment?
1 (type a whole number.)
in the table below, name the factor(s) and the number of levels of each.
factor number of levels (type a whole number )

Explanation:

Part b)

To identify the subjects, we analyze the research context: the study involves 100 people with a psychological disorder who are given different treatments (supplement or placebo). Option A is incorrect as psychological disorders are not the subjects (they are the condition of the subjects). Option C refers to a population, but the study uses 100 specific people (a sample), not the entire population. Option D is incorrect as dietary supplements are the treatment, not the subjects. So the subjects are the 100 people with a psychological disorder.

Step1: Identify the factor

The experiment manipulates the type of treatment (dietary supplement or placebo, along with the dosage for the supplement). The factor here is the "treatment" (or "dosage/treatment" related to the dietary supplement and placebo).

Step2: Determine levels

The levels are the different groups: high - dose dietary supplement and placebo. So there are 2 levels for this factor (since we have two distinct treatments: high - dose supplement and placebo).

Answer:

B. The subjects are 100 people with a psychological disorder.

Part c)