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help for ^kr20^
by Herve M. CACI, August 1999 (v1.2)
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Kuder-Richardson coefficient of reliability
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^kr20^ varlist [^if^ exp][^in^ range], [sort(sortkey)]
Description
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Computes the reliability coefficient of a set of dichotomous items, whereas
Cronbach's alpha is used for multipoint scales.
In addition, ^kr20^ computes:
- the item difficulty (proportion of 'right' answers),
- the average value of item difficulty,
- the item variance,
- the corrected item-test point-biserial correlation coefficients,
- the average value of corrected item-test correlation coefficients.
The items must be coded as:
- '0' for a wrong answer (unexpected answer),
- '1' for a right answer (expected answer).
Global macros
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KR20 saves four results in the following global macros
- $S_3: average value of item difficulties
- $S_4: average value of corrected item-test PB correlation coefficients
- $S_5: number of items
- $S_6: KR20
Options
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^sort(sortkey)^ to sort the output by 'item' name (alphabetically), or by
'DIFFiculty' level or 'CORRelation' coefficient.
Also see
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STB: ^alpha2^ in sg66 (STB-35)
Manual: ^[R] alpha^
On-line: help for @factor@