Question

a researcher is studying people of normal weight and obese individuals. She wants to know how the time of day affects hunger feelings in the two groups. When, during the experiment, the researcher looks at her watch, she has introduced a/an __________ into the research study.
A.) placebo effect
B.) control
C.) Volunteer bias
D.) experimenter effect

I think it is D. But not sure/

Answer 1

I agree.