# Notes - M ay 12 2009 To Establish Causality Variabl es must...

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May 12, 2009 To Establish Causality: - Variables must be related (x correlated with y) o Surveys can show that o Ex. increased studying and increased GPA - Must establish time order o IV happened before DV - Must rule out other explanations/causes Survey/Correlational Research – 2 Causality Problems: - Causal direction problem (time order) o Does x cause y or does y cause x - Third variable problem (other explanations) o Does some “third” variable explain the x/y relationship? Getting Closer to Causality: - Solve third variable problem o Partial correlation Measure potential third variables Statistically control for effects of those third variables Then see if x/y relationship still holds o Partial Correlation GPA Time Studying Interest in School Block out third circle o If x/y relationship still holds, can rule out third variable as the cause o If x/y relationship disappears (or reduced substantially) then the third variable explanation matters

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• Spring '09
• DorothyMullin
• Causality, Correlation does not imply causation, internal validity, X/Y relationship, variable problem

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Notes - M ay 12 2009 To Establish Causality Variabl es must...

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