help for ^kr20^
by Herve M. CACI, August 1999 (v1.2)

Kuder-Richardson coefficient of reliability -------------------------------------------

^kr20^ varlist [^if^ exp][^in^ range], [sort(sortkey)]

Description -----------

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 -------------

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 -------

^sort(sortkey)^ to sort the output by 'item' name (alphabetically), or by 'DIFFiculty' level or 'CORRelation' coefficient.

Also see --------

STB: ^alpha2^ in sg66 (STB-35) Manual: ^[R] alpha^ On-line: help for @factor@