Multivariate Methods • Correlations and Multivariate Techniques • Computations and Statistical Details • Cronbach’s α
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Cronbach’s α
Cronbach’s α is defined as
where
k = the number of items in the scale
c = the average covariance between items
v = the average variance between items
If the items are standardized to have a constant variance, the formula becomes
where
r = the average correlation between items
The larger the overall α coefficient, the more confident you can feel that your items contribute to a reliable scale or test. The coefficient can approach 1.0 if you have many highly correlated items.

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Help created on 9/19/2017