A serious weakness of the pretest-posttest, natural control-group design is that
A) the two groups may be statistically different from each other at the start of the study.
B) the two groups may be statistically equivalent at the start of the study.
C) experimenter effects cannot be prevented.
D) there is no control for effects due to history or maturation.
Answer: A
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The Supreme Court's Dred Scott v. Sandford (1857) decision narrowed the scope of the federal government's power by determining that __________
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