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15 Cards in this Set
- Front
- Back
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An item difficulty index of .80 indicates that ____% of examninees answered item CORRECTLY
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80%
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what item difficulty index represents the MOST differentiation the item makes between examinees?
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.50
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what is the optimal item difficulty level?
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.50
note: except for true/false questions... then it's .75 |
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classical test theory
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obtained test score reflects combination of truth & error
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what theory is item difficulty, reliability, & validity based on?
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classical test theory
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item response theory
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item characteristics stay the same accross samples ie sample-invariant
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methods used to evaluate reliability
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test-retest
alternate forms split-half (e.g. Spearman-Brown) coefficient alpha (e.g. Kuder-Richardson Formula 20) inter-rater |
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what does a reliability coefficient of .80 mean?
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80% of variability in test scores is due to differences in true scores.
20% due to measurement error |
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which method of reliability is NOT appropriate for speed tests
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internal consistency
i.e. split-half |
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which method of reliability is considered to be the most thorough?
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alternate forms
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what is the lowest reliability coefficient to be considered acceptable?
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.80
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what is a standard error of measurement for?
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to calculate a confidence level around an examinee's score
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confidence intervals
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68% +/- 1 standard error
95% +/- 2 standard errors 99% +/- 3 standard errors |
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when would you use criterion-related validity
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to predict scores on some other measure
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2 methods used to test construct validity
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2. convergent & divergent validity othersise known as, Multitrait-Multimethod Matrix
2. factor analysis |
