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Based on this scenario, decide what specific alternative to simple random assignment Dr. Smith should implement to eliminate this risk, and justify how the mechanics of this alternative directly solve the problem.
Case context: Dr. Smith is conducting a between-subjects experiment to evaluate a new behavioral intervention for anxiety. With a limited pool of participants, Dr. Smith is concerned that simple random assignment might accidentally place a disproportionate number of highly anxious individuals into the control group, compromising the study's internal validity.
Question: Based on this scenario, decide what specific alternative to simple random assignment Dr. Smith should implement to eliminate this risk, and justify how the mechanics of this alternative directly solve the problem.
Sample answer: Dr. Smith should implement a matched-groups design. By measuring the participants' baseline anxiety levels first, rank-ordering them, and then randomly assigning the most closely matched individuals to the different conditions, Dr. Smith guarantees that the experimental and control groups are equivalent in terms of baseline anxiety. This prevents baseline anxiety from becoming a confounding variable, effectively solving the vulnerability of simple random assignment in small samples.
Key points:
- Identify the matched-groups design as the correct methodological alternative.
- Explain the need to measure the baseline anxiety variable first.
- Describe rank-ordering the participants based on their anxiety scores.
- Explain that matched individuals are randomly assigned to different conditions.
- Conclude that this guarantees equivalent groups and prevents confounding variables.
Rubric: The response must explicitly identify the matched-groups design and demonstrate comprehension by explaining how the process of measuring, ranking, and assigning matched individuals ensures initial group equivalence on the targeted variable.
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Research Methods in Psychology - 4th American Edition @ KPU
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Example of a Matched-Groups Design
Arrange the steps involved in executing a matched-groups design in the correct order.
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In a matched-groups design where participants are paired based on their 'baseline anxiety levels,' the resulting groups are guaranteed to be equivalent regarding their anxiety, but they are not guaranteed to be equivalent regarding other factors like 'intelligence' or 'motivation.'
Which between-subjects experimental design requires researchers to first measure participants on a specific variable, rank-order them based on their scores, and then randomly assign the most closely matched individuals to the different treatment groups?
In a matched-groups design, because participants are paired based on their similarity on a key variable, the researcher systematically assigns one member of each pair to the experimental group and the other to the control group, completely eliminating the need for random assignment.
In a methodological critique of an experiment with a very small sample size, a researcher concludes that simple random assignment was an inadequate choice for controlling a highly influential extraneous variable. To justify a more rigorous approach, the researcher would evaluate a(n) _____ design as the most appropriate substitute for ensuring that the groups are equivalent on that specific variable from the outset.
An educational psychologist is comparing two different reading programs. To control for prior reading ability, they implement a matched-groups design. Match each phase of their methodology to its corresponding description or function in this design.
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Evaluate the chronological methodology required to implement a matched-groups design. Arrange the steps a researcher must take, from the initial setup to the final group placement, to ensure group equivalence on a targeted variable.
Provide a concise analytical response describing the sequence of methodological steps a researcher must take to execute a matched-groups design, and state the primary purpose of using this design instead of simple random assignment.
Based on this scenario, decide what specific alternative to simple random assignment Dr. Smith should implement to eliminate this risk, and justify how the mechanics of this alternative directly solve the problem.
A researcher is planning a between-subjects experiment to test two different puzzle-solving strategies and wants to control for baseline spatial reasoning skills. In one to three sentences, describe exactly how the researcher would apply a matched-groups design to assign participants to the two strategies.