Lecture 22 - Experimental Control_New

Lecture 22 - Experimental Control_New - Psych 301W Lecture...

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Psych 301W – Lecture 22 Fall 09 - Wede Lecture 22 – Experimental Control Experimental control Occurs to the extent the experimenter is able to eliminate effects on the dependent variable other than the effects of the independent variable Extraneous variables Variables other than the independent variable causing changes in the dependent variable Include both initial differences among the research participants and differences in how the experimenter treats the participants or how they react to the experimental setting Confounding variables Variables other than the independent variable on which the participants in one experimental condition differ systematically or on average from those in other conditions Unintentionally created by the experimental manipulations Confounding and Internal Validity Confounding When another variable in addition to the independent variable of interest differs systematically across the experimental conditions Impossible to determine which of the variables has produced changes in the dependent variable Internal validity Extent to which changes in the dependent variable can confidently be attributed to the effect of the independent variable, rather than to the potential effects of confounding variables Alternative explanations Presence of a confounding variable does not necessarily mean the independent variable did not cause the changes in the dependent variable Confounding variables always produce potential alternative explanations for the results
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Lecture 22 - Experimental Control_New - Psych 301W Lecture...

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