Problem
Many students enrolled in a psychology course are considering participating in a research project for the professor. What strategies could the professor use to prevent students from feeling coerced to participate? Select all that apply.
a) Add 5% to students' course grades as an incentive for participating in the study
b) Use a research assistant to recruit students to participate in the study
c) Inform students that they will not be penalized if they choose not to participate
d) Allow participating students to withdraw from the study at any time.