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Reliability

Reliability. Consistent Dependable Replicable Stable . Two Administrations. Test/retest same test - same group Parallel/Alternate forms different versions of test - same group. Two administration procedure:. Administer tests (in two sessions) Convert to z scores (if necessary)

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Reliability

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  1. Reliability • Consistent • Dependable • Replicable • Stable

  2. Two Administrations • Test/retest same test - same group • Parallel/Alternate forms different versions of test - same group

  3. Two administration procedure: • Administer tests (in two sessions) • Convert to z scores (if necessary) • Correlate (Pearson or Spearman)

  4. Two administration issues: • Problems????? • Duration between???? • Type of variable?????

  5. One Administration • One test • One group • One administration

  6. 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

  7. Uses of one administration: • Internal consistency of items • What types of tests to use this on???

  8. Inter item consistency • Statistical estimation • Kuder-Richardson Formula 20 (KR20) = dichotomous questions • Cronbach alpha (alpha coefficient) = all questions • (factor analysis)

  9. Reliability coefficient • 0.00 - 1.00 • higher is better • score is relative, not absolute

  10. Inter-rater reliability • Consensus between raters • Percentage of agreement • Kappa statistic (2 or many raters)

  11. Threats to reliability • Construction • Administration (tester, testee, environment) • Scoring • Interpretation

  12. Project homework • 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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