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Define a posttest only nonequivalent groups design and state why inherent differences may exist between the groups from the beginning of a study.
Question: Define a posttest only nonequivalent groups design and state why inherent differences may exist between the groups from the beginning of a study.
Sample answer: A posttest only nonequivalent groups design is a quasi-experimental approach where one group receives a treatment and is compared to a nonequivalent control group that did not receive the treatment. Because researchers do not use random assignment to allocate participants to these groups, inherent differences may exist between them from the very beginning.
Key points:
- It is a quasi-experimental approach.
- One group receives a treatment.
- The treatment group is compared to a nonequivalent control group that did not receive the treatment.
- The researcher does not use random assignment.
- The lack of random assignment causes inherent differences to potentially exist from the beginning.
Rubric: Award full credit for identifying the design as a quasi-experimental approach that compares a treated group to an untreated nonequivalent group, and for explicitly attributing potential initial group differences to the lack of random assignment.
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Research Methods in Psychology - 4th American Edition @ KPU
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