alpha | R Documentation |
Coefficient alpha is a measure of internal consistency. It is a standard measure of reliability for tests.
alpha(x)
x |
Data.frame or matrix object with rows corresponding individuals and columns to items |
You can specify any portion of a matrix or data.frame. For instance, if using a data.frame
with numerous variables corresponding to items, one can specify subsets of those items. See examples
below.
alpha <- k/(k-1)*(1-SumSxi/Sx)
where k is the number of items, Sx is the standard deviaton of the total test, and SumSxi is the
sum of the standard deviations for each item.
coefficient alpha
Thomas D. Fletcher t.d.fletcher05@gmail.com
Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 6, 297-334.
alpha.CI
data(attitude)
alpha(attitude)
alpha(attitude[,1:5])
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