Question

observational studies allow scientists to study systems as a whole while observing and recording data. some research questions require that scientists conduct an experimental study. in an experimental study, scientists manipulate variables to understand the relationship between the variables.

what additional factor, which is not a concern in observational studies, must scientists consider when conducting experimental studies on animal or human subjects?
○ scientists must consider that in order for the study to be published, it must be subjected to peer review.
○ scientists must consider the ethical ramifications of the study by weighing the benefits of the research against the liability of adverse effects on the subjects.
○ scientists must consider how to select a test group and a control group, as well as how to determine the independent and the dependent variables to be tested.
○ scientists must consider the costs and logistics of the study, as well as any incidental expenditures.

Explanation:

1. Analyze Option 1: Peer review is a publication - related process, not a factor unique to experimental studies on human/animal subjects compared to observational studies. Both observational and experimental studies may undergo peer review for publication.
2. Analyze Option 2: In experimental studies on human or animal subjects, scientists manipulate variables. This manipulation can potentially harm the subjects. So, ethical ramifications (weighing research benefits against adverse effects on subjects) are a key concern. In observational studies, since there is no manipulation of variables, this ethical consideration related to variable manipulation is not present.
3. Analyze Option 3: Selecting test/control groups and determining variables is part of the experimental design process, but it is not a factor that is not a concern in observational studies. Observational studies also have considerations about sampling and variables (though they don't manipulate them).
4. Analyze Option 4: Costs and logistics are concerns for both observational and experimental studies, not unique to experimental studies on human/animal subjects.

Answer:

B. Scientists must consider the ethical ramifications of the study by weighing the benefits of the research against the liability of adverse effects on the subjects.