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Reliability if deleted, not 'alpha if deleted': evaluation of scale reliability following component deletion
1Michigan State University, East Lansing, MI 48824, USA. raykov@msu.edu
Abstract:
This paper demonstrates that the widely available and routinely used index 'coefficient alpha if item deleted' can be misleading in the process of construction and revision of multiple-component instruments with congeneric measures. An alternative approach to evaluation of scale reliability following deletion of each component in a given composite is outlined that can be recommended in general for scale development purposes. The method provides ranges of plausible values for instrument reliability when dispensing with single components in a tentative composite, and permits testing hypotheses about reliability of resulting scale versions. The proposed procedure is illustrated with an example.
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