Threats to Internal Validity

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Threats to Internal Validity
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Between-groups Design
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Within-groups Design(Repeated Measures)
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Campbell Stanleys 8 Threats to Internal
Validity

• 1) _________
• Groups _______ before the study began
• Dont allow _____-________
• Dont allow arbitrary assignment
• Use ________ assignment

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8 Threats to Internal Validity

• 2) Selection X __________
• Experimental and control groups have ________
  _______apart (developed differently)
• Difference is due to developmental change, not
  ___________

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8 Threats to Internal Validity

• 3) _________ Effects
• Tendency for ________ scores to revert back to
  ________ levels
• Cover of Sports Illustrated Example

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8 Threats to Internal Validity

• 4) ________
• Groups differ due to
• ______ of participants
• throughout study

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8 Threats to Internal Validity

• 5) ___________
• Change in participants due to _______ causes not
  treatment
• Examples physical, biological changes
  (hungrier, older, bored)

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8 Threats to Internal Validity

• 6) ________
• Participants change due to _______ occurring in
  outside world, environment
• Example 9/11

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8 Threats to Internal Validity

• 7) ________
• ________ itself changes participants
• Practice Effect _________ effect caused by
  previous experience with the dependent measure

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8 Threats to Internal Validity

• 8) ___________
• Changes in ___________ can change participant
  responses
• Example change in researchers, measurement tool