To avoid bias and confounds in a controlled experiment, ...

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To avoid bias and confounds in a controlled experiment, participants should be assigned to either the experimental or control group ____.
 
  a. on the basis of careful thought
  b. randomly
  c. on the basis of individual tests
  d. according to age variables

Question 2

Derrill is worried that variables such as age, gender, personality characteristics, and education level might confound the results of his experiment, which is designed to test the effects of mood on reaction time. Derrill should use ____ assignment to experimental groups to distribute the impact of these ____ variables.
 
  a. random; representative
  b. representative; random
  c. representative; representative
  d. random; random

[morrie123456]

Answer to Question 1

ANSWER:
b

Answer to Question 2

ANSWER:
d