Cronbach's alpha is a statistical measure used to assess the reliability or internal consistency of a set of items, such as survey questions or test items. It ranges from 0 to 1, where higher values indicate greater reliability. A commonly accepted threshold for good reliability is 0.70 or above, suggesting that the items measure the same underlying concept. Researchers often use Cronbach's alpha to ensure that their instruments yield consistent results across different populations or settings. It helps identify whether the items in a questionnaire or test are effectively capturing the intended construct, making it a valuable tool in fields like psychology, education, and social sciences.