TimelyScholarFree Tools › Cronbach's Alpha Calculator
Check the internal consistency of a questionnaire or scale. Paste item scores to get Cronbach's alpha with a 95% confidence interval, standardized alpha, item-total correlations and alpha if each item is deleted.
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| Cronbach's alpha | 0.746 (95% CI 0.567 to 0.865) |
|---|---|
| Standardized alpha | 0.761Based on the mean inter-item correlation |
| Mean inter-item correlation | 0.390 |
| Items and respondents | 5 items, 30 complete responses |
| Item | Mean | SD | Corrected item-total r | Alpha if item deleted |
|---|---|---|---|---|
| q1 | 2.83 | 1.39 | 0.402 | 0.757 |
| q2 | 2.70 | 0.95 | 0.627 | 0.668 |
| q3 | 2.80 | 1.10 | 0.488 | 0.709 |
| q4 | 2.77 | 1.01 | 0.568 | 0.683 |
| q5 | 3.00 | 1.17 | 0.534 | 0.692 |
Reported acceptable values of alpha range from about 0.70 to 0.95; a very high alpha (above 0.90) can mean some items are redundant. Items with a low corrected item-total correlation, or whose removal raises alpha (in bold), are candidates for review. Alpha assumes the scale measures a single construct.
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Cronbach's alpha estimates how consistently a set of items measures the same construct. It rises with more items and stronger correlations between items.
Reported acceptable values range from about 0.70 to 0.95. A very high alpha may mean some items are redundant, and a maximum of 0.90 has been recommended. Alpha assumes the items measure a single construct, so check dimensionality first.
Items with a low corrected item-total correlation, or whose removal raises alpha, are candidates for revision. Reverse-score negatively worded items before calculating.
Values from about 0.70 to 0.90 are usually considered acceptable to good for research scales; the right threshold depends on the purpose of the scale.
Usually because some items are negatively worded and have not been reverse-scored.