Impact of the number of response categories and anchor labels on coefficient alpha and test-retest reliability

A total of 1,247 college students participated in this study on the effect of scale format on the reliability of Likert-type rating scales. The number of response categories ranged from 3 to 9. Anchor labels on the scales were provided for each response option or for the end points only. The results indicated that the scales with few response categories tended to result in lower reliability, especially lower test-retest reliability. The scales with all the response options clearly labeled were likely to yield higher test-retest reliability than those with only the end points labeled. Scale design that leads to consistent participant responses as indicated by test-retest reliability should be preferred.