Talk:Kuder–Richardson formulas

Latest comment: 1 year ago by Michael Hardy in topic What is "Xi"?

Formula Explanation

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Yet another article giving a formula without explaining all the variables. Pi and Qi would seem to be the proportion of people getting an item correct or incorrect as described here [[1]] . It might also be helpful to indicate the variance and associated sum of squares are applied to raw scores with N being the number of people in the sample (not number of test items). —Preceding unsigned comment added by 98.231.152.208 (talk) 15:11, 22 October 2010 (UTC)Reply

Also why the name

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Rather unusual name - is there some history behind this? What were KR1 to KR19? — Preceding unsigned comment added by 31.221.13.140 (talk) 09:48, 11 May 2012 (UTC)Reply

What is "Xi"?

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This article says

The formula for KR-20 for a test with K test items numbered i = 1 to K is

 

where pi is the proportion of correct responses to test item i, qi is the proportion of incorrect responses to test item i (so that pi + qi = 1), and the variance for the denominator is

 

where n is the total sample size.

It never says what   is! Are there people who can read something like that without feeling they're being personally abused? Michael Hardy (talk) 16:03, 8 July 2023 (UTC)Reply