Question

a dietary researcher studying grocery expenses is interested in the possible effect that having a vegetarian diet has on a single (unmarried) persons monthly grocery bill. to investigate, the researcher conducts an observational study by contacting a sample of 400 single adults who are homeowners. the researcher gathers the following information from each participant: dietary habits (vegetarian or meat - eater), monthly grocery bill, yearly income and education level. from the data, the researcher creates two groups: vegetarians and meat - eaters. then he compares the average monthly grocery bill between the two groups.
(a) why might the researcher have chosen to perform an observational study (by gathering information about participants current behaviors) and not a randomized experiment (by assigning participants to either the vegetarian or meat - eating group at random)? choose the best answer from the choices below.
in a randomized experiment, it could be that some participants who do not eat meat would be assigned to the meat - eating group, meaning that theyd be forced to eat meat. it would not be ethical to force people to eat meat.
a randomized experiment should never be performed when it is possible to perform an observational study. when groups are randomly assigned, the researcher cannot control the types of participants in each group, making the results of a randomized experiment unreliable.
for a randomized experiment to be performed, the researcher must ask people in the population to volunteer to take part. this would mean that there would not be any chance to include vegetarians in the sample.

Explanation:

Randomized experiments require random assignment of participants to groups. In this case, forcing non - meat eaters to eat meat is unethical. Observational studies are better when manipulation of behavior (like diet) is unethical. Randomized experiments also need proper random selection from the population, and if not done right, results can be unreliable.

Answer:

In a randomized experiment, it could be that some participants who do not eat meat would be assigned to the meat - eating group, meaning that they'd be forced to eat meat. It would not be ethical to force people to eat meat. A randomized experiment should never be performed when it is possible to perform an observational study. When groups are randomly assigned, the researcher cannot control the types of participants in each group, making the results of a randomized experiment unreliable. For a randomized experiment to be performed, the researcher must ask people in the population to volunteer to take part. This would mean that there would not be any chance to include vegetarians in the sample.