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Kuder-Richardson #21 Formula for estimate test reliability
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JE McGimpsey
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Kuder-Richardson #21 Formula for estimate test reliability
One way:
=(k/(k-1)) * (1 - (X*(k-X))/(k*S))
You can either name your cells k, X, and S, or replace the k,X,S in the
formula with cell references.
In article . com,
wrote:
Good Morning!
I am trying to figure out how to adapt the Kruder-Richardson Formula
#21 to excel. First of all this is not a homework assignment.
Secondly, I appologize for linking a file but I could not get the
fonts for the formula right. What the formla does is to estimate test
reliability. I can figure it out long hand but would greatly
appreciate it in excel thanks in advance.
R=( k) (1- X(k-X))
----- -----------
k-1 kS
where
R= test reliability
k = number of items on the test
X = mean of raw scores from the total test
S = vfariance from the raw scores of the total test
Suppose we had a 50 item test and the mean score was 43 and the
variance was 25.0. We would have
R= (50) (1- 43(50 - 43))
----- --------------
50-1 (50)(25)
R = (1.02) (1- 301)
----
1250
R = (1.02) (0.76) = 0.78
Thank you in advance.
http://www.savefile.com/projects/808560688
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