If a researcher discovers that a variable that is not of interest ...

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If a researcher discovers that a variable that is not of interest in a study may be affecting the dependent variable, that researcher
 
  a. can rule out causal ambiguity.
  b. should invoke the temporal precedence rule.
  c. has identified a possible extraneous variable.
  d. should use a double blind study to overcome the problem.

Question 2

Researchers have discovered that children experiencing Attention Deficit Hyperactivity Disorder (ADHD) show improvements if they attend classes on involving behavioral and social skills, compared to a group of ADHD children who did not attend the classes.
 
  The group of children who did not attend the classes constitute the
  a. experimental group.
  b. independent group.
  c. control group.
  d. randomized group.

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Answer to Question 1

c

Answer to Question 2

c