Calculates Cronbach's alpha and standardized alpha (lower bounds on reliability)
for a composite (summated-rating) scale. Standardized alpha is for the sum of the
standardized items. In addition, the function calculates alpha and standardized
alpha for the scale with each item deleted in turn, and computes the correlation
between each item and the sum of the other items.
Usage
reliability(S)
Arguments
S
the covariance matrix of the items
Value
The function does not return a useful value; it is called
for its side effect -- to print the results.
References
N. Cliff (1986) Psychological testing theory. Pp. 343--349 in
S. Kotz and N. Johnson, eds., Encyclopedia of Statistical Sciences, Vol. 7.
Wiley.