Why is research involving already existing groups rather than randomly assigned groups prone to the effects of extraneous variables?
What will be an ideal response?
When you use existing or intact groups, you don't have a guarantee that they are equivalent; that is, if you were to measure then on the DV, they might differ from the start. If you didn't know about this difference, you would mistakenly attribute a difference at the end of the study to the IV.
When groups are created by random assignment, there is less chance that the groups will differ systematically because differences that could be critical are spread out randomly across groups.
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Fill in the blank with the appropriate word.
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Indicate whether the statement is true or false
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a. the Annual Performance Review. b. the State of the Union address. c. the Appeal to the Nation. d. Review of Congress. e. Face the Nation.