Verbal estimates of probability (such as likely or certain) commonly used in laboratory, radiological, and clinical reports may be a barrier to effective communication between health care professionals. In this study the investigators sought to determine whether a consensus of numerical meaning existed in a sample of nurses for each of 30 widely used verbal expressions of probability. Seventy female nurses enrolled in a graduate course were surveyed by means of a test-retest procedure using a questionnaire designed to elicit assignments of numerical probability (0% to 100%). The results showed wide inconsistency both between subjects and within subjects.