This measures the internal consistency on a scale. It is often used when you have multiple Likert questions in a questionnaire that form a scale and you wish to test the reliability of the scale. Example is when the answer of a question range from “strongly agree” to “strongly disagree”.
- Click Analyze- Scale- choose Reliability Analysis
- Transfer the variables into the Items box.
- Leave the model set as “Alpha”, this represents Crohnbach’s alpha, you can choose the name of your scale in the Scale label
- Click the Statistic button to open the Reliability Analysis dialogue box
- Select the Item, Scale, Scale if item delete, and Correlation
- Click the Continue button
- Click Ok to generate the output.
From the reliability statistic table, A high value of Crohnbach’s alpha indicates a high level of internal consistency. The item-total-statistic table shows the value of Crohnbach’s alpha if the particular item was deleted.