Troubleshooting
Problem
I want to obtain a confidence interval for Cronbach's alpha in SPSS. Are bootstrapped confidence intervals available for alpha?
Resolving The Problem
Cronbach's alpha is identical to the intraclass correlation coefficient (ICC), when the ICC is calculated using either the two-way mixed consistency or two-way random consistency models. ICCs can be obtained through dialogs by clicking on the Statistics button under Analyze > Scale > Reliability Analysis, and checking the "Intraclass Correlation Coefficient" checkbox. A total of five ANOVA models are available through which the ICC may be calculated; as long as one chooses a two way consistency model (this is done through the two dropdowns labeled "Model" and "Type" just below the ICC checkbox), you will see in the output table titled "Intraclass Correlation Coefficient" a line labeled "Average Measures". The ICC on this line will be identical to Cronbach's Alpha, and a confidence interval is reported for the ICC; hence this is a CI for Alpha as well.
Bootstrapping is not currently (as of Statistics v. 23) available for the Reliability procedure.
Related Information
Historical Number
62946
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Document Information
Modified date:
16 April 2020
UID
swg21478552