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Unformatted text preview: 2-8-11Extraneous Variables (Confounders)oDifference between groups can cause the distributions to be closer together or farther apart; This can be the result of the IV or the EVoNo way to tell which caused the differenceoExtraneous Variable (EV) uncontrolled variables that can cause unintended changes between groupsoConfounded when you dont know whether the IV or the EV caused the differenceoBook example: Reading ComprehensionoStandard method of teaching used with 1stgraders and the New method is used with the 2ndgraders. We find a difference between the two groups. What is the EV in this example? Grade levelo(Diagram in book)oDifference between two groups with no confounder operatingoDifference between two.oNuisance Variables vs. Extraneous VariablesoExample 1oIV: list of words with no slow synonyms; List of words only slow synonymsoDV: Reaction timeoNV: Age of all participants in both conditions is random mix of 12-78 yr oldsoEV: age could be alternate explanation for the difference if one group is all senior citizens and other college studentsoExample 2oIV: words flash on screen count letters; words flash on screen put them in sentenceoDV: recall a list of wordsoNV: The elevator goes off randomly when people ride I during both...
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This note was uploaded on 04/05/2012 for the course PSY 3213 taught by Professor Staff during the Spring '11 term at FSU.
- Spring '11