Chapter 5 - Skeleton (1)

Chapter 5 - Skeleton (1) - Psy250: Scientific Inquiry...

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Psy250: Scientific Inquiry Chapter 5 Measurement Concepts
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Notes About Participation Assignment From Last Class
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Measurement Concepts Many ways to measure variables (and many variables to be measured) Ask people (self-report) Physiological measures Neurological activity Behavioral measures Need to consider the reliability, validity, and reactivity of our measures
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Reliability of Measures Reliability: Consistency or stability of a measure of behavior. A reliable measure will yield the same result each time you administer it to the same person a reliable measure does not fluctuate. Fluctuations reflect error in the measurement device
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Reliability of Measures Any measurement that you make has two components: 1) true score:- an individual’s real score on a variable. 2) measurement error:- unreliable measure contains considerable measurement error; reliable measure contains little measurement error. research typically only get 1 chance at measuring each person – can’t measure everyone many times and discover their true score.
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Reliability of Measures An unreliable measure of a variable in psychological research is useless Cannot use an unreliable measure to systematically study variables or the relationship between variables Unreliable measures will lead to unstable results that are difficult to replicate
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Reliability of Measures How to achieve reliability: use careful measurement procedures. When using questioners, reliability increases as # of questions(items) increase. *Sadly, it is not possible to directly observe the true score and error components of a score on a measure We can assess stability of measures using correlation coefficients
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Assessing Reliability Correlation coefficient: # that tells how strong 2variables are related to one another. Pearson product-moment correlation coefficient Can range from -1.00 to 1.00 Closer to -1.00 or 1.00, stronger the relationship When correlation coefficient is positive (+ sign) there is positive linear relationship between variables When correlation is negative (- sign), there is a negative linear relationship
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Assessing Reliability Need to obtain at least two scores on the measure from many individuals Reliable measure: scores should be very similar(highly positively correlated) - Reliability coefficient: correlation coefficient used to describe reliability of a measure. *Test-Retest Reliability Internal Consistency Reliability Interrater Reliability
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Assessed by measuring the same individuals at two points in time Then calculate a correlation coefficient between the original test score and the retest score High reliability indicated by high correlation coefficient indicating 2scores very highly similar correlation should be at least 0.80
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This note was uploaded on 03/10/2011 for the course PSY 250 taught by Professor Briannalharris during the Summer '10 term at State University of New York.

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Chapter 5 - Skeleton (1) - Psy250: Scientific Inquiry...

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