Question

Why do psychologists use random assignment?

A. To make sure that any pre-existing differences will balance out among the groups.
B. To make sure each person has an equal chance of participating in the study.
C. To make sure experimenter bias does not affect the results of the study.
D. To be able to assign participants to conditions based on their group membership.

Answer 1

Psychologists use random assignment in experimental design to balance out pre-existing differences among groups, ensure equal chance of participation, and assign participants based on group membership.

Step-by-step explanation:

Psychologists use random assignment in experimental design for several reasons:

1. To make sure that any pre-existing differences will balance out among the groups. Random assignment makes it unlikely that there are systematic differences between the groups, such as gender, ethnicity, or religious beliefs.
2. To make sure each person has an equal chance of participating in the study. Random assignment ensures that all participants have an equal chance of being assigned to either the experimental or control group.
3. To be able to assign participants to conditions based on their group membership. With random assignment, researchers can assign participants to different treatment groups based on their group membership in a way that balances out potential lurking variables and allows for cause-and-effect relationships to be inferred.