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Related Flashcards
Related Topics
Cards In This Set
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• Deals with experimental control• Extent to which we can be sure the IV is the cause of the DV
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Internal validity
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• Deals with generalizeability• Extent to which we can be sure we can generalize our results to different population |
External validity
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Two ways of establishing internal validity
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1. Controlling for extraneous variables2. Choose a good research design
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What is your goal when it comes to internal validity
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– Provide an alternate explanation for the results– Come up with an improvement to the procedure that would eliminate this explanation
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If groups are not equal prior to the experiment, don’t know whether results are a function of the IV or the pre-existing differences
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Selection
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When events occur in the course of an experiment (after the IV manipulation but before the DV measure is taken) that affect the DV
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History
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– When changes occur in the participants over time during their participation in the experiment that affect the DV
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Maturation
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When measuring the DV causes a change in the DV
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Testing
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When the measurement criterion is changed during testing
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Instrument
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When people with extreme scores are measured multiple times their scores tend to drift closer to the mea
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Regression to the mean
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When participants from different groups drop out of the experiment at different rate
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Experimental mortality
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When systematic differences exist between or among groups based on maturation, history, or instrumentation
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Interactions with selection
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8 types of threat to his internal validity
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- selection - history - testing - maturation - instrument- regression to the mean - experimental mortality - interactions with selection
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What is the most obvious fix for threats to internal validity?
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Random assignment
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Every member of a group has an equal probability of being assigned to any group
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Random assignment
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