Compute the stratified Cronbach's coefficient alpha for a test composed of
several item strata (e.g., subtests or subscales).
Usage
stratified_alpha(x, s)
Value
A named list with:
stratified_alpha
Stratified Cronbach's coefficient alpha.
Arguments
x
A data frame or matrix containing item responses, with rows as
subjects and columns as items. Items are assumed to be ordered by stratum.
s
A numeric vector giving the number of items in each stratum. The
sum of s must equal ncol(x).
Details
Stratified alpha is an estimate of the internal consistency reliability of a
composite test formed by multiple item strata (e.g., subtests). Each stratum
reliability is computed using alpha(), and combined using the
classical stratified-alpha formula.