Wendy wants to study how easily people make friends. She assigns people to talk with a stranger for either five minutes or ten minutes, and assigns people who are more outgoing to the five-minute condition, and shy people to the ten-minute condition.
Which of the following is the threat to the internal validity in this study?
a. The independent variable isn't held constant for every participant in a condition.
b. Dependent variables are not being assigned randomly.
c. She did not select from a random sample in her population.
d. Wendy did not use random assignment.
Question 2
________ and ________ are the hallmarks of the experimental method, which set it apart from the observational and correlational methods.
a. Random assignment; probability levels
b. Representative sampling; control over extraneous variables
c. Control over extraneous variables; random assignment
d. Correlation coefficients; dependent variables
Lynx-hare interactions have served as a model system for the study of the effects o
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