Reliability n Consistent n Dependable n Replicable n Stable.
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Presentation on theme: "Reliability n Consistent n Dependable n Replicable n Stable."— Presentation transcript:
Reliability n Consistent n Dependable n Replicable n Stable
Two Administrations n Test/retest same test - same group n Parallel/Alternate forms different versions of test - same group
Two administration procedure: n Administer tests (in two sessions) n Convert to z scores (if necessary) n Correlate (Pearson or Spearman)
Two administration issues: n Problems????? n Duration between???? n Type of variable?????
One Administration One test One test One group One group One administration One administration
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
Uses of one administration: n Internal consistency of items n What types of tests to use this on???
Inter item consistency n Statistical estimation Kuder-Richardson Formula 20 (KR20) = dichotomous questions Cronbach alpha (alpha coefficient) = all questions n (factor analysis)
Reliability coefficient n 0.00 - 1.00 n higher is better n score is relative, not absolute
Inter-rater reliability n Consensus between raters n Percentage of agreement n Kappa statistic (2 or many raters)
Threats to reliability n Construction n Administration (tester, testee, environment) n Scoring n Interpretation
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?