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Reliability n Consistent n Dependable n Replicable n Stable
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Two Administrations n Test/retest same test - same group n Parallel/Alternate forms different versions of test - same group
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Two administration procedure: n Administer tests (in two sessions) n Convert to z scores (if necessary) n Correlate (Pearson or Spearman)
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Two administration issues: n Problems????? n Duration between???? n Type of variable?????
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One Administration One test One test One group One group One administration One administration
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One administration procedure: Administer test to one group Divide questions to score Split Half first/second or odd/even halves???? Correlate scores from halves Apply Spearman-Brown formula estimate changes in length
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Uses of one administration: n Internal consistency of items n What types of tests to use this on???
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Inter item consistency n Statistical estimation Kuder-Richardson Formula 20 (KR20) = dichotomous questions Cronbach alpha (alpha coefficient) = all questions n (factor analysis)
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Reliability coefficient n 0.00 - 1.00 n higher is better n score is relative, not absolute
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Inter-rater reliability n Consensus between raters n Percentage of agreement n Kappa statistic (2 or many raters)
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Threats to reliability n Construction n Administration (tester, testee, environment) n Scoring n Interpretation
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Project homework n Which approaches were used to determine the reliability of your measure? Why were those measures selected? Could they have used other measures? Why/why not?
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