PURPOSE: The annual meeting of the American Society for Radiation Oncology (ASTRO) is designed to disseminate new scientific findings and technical advances to professionals. Best practices of scientific dissemination require that some level of uncertainty (or imprecision) is provided. METHODS AND MATERIALS: A total of 279 scientific abstracts were selected for oral presentation in a clinical session at the 2013 ASTRO Annual Meeting. A random sample of these abstracts was reviewed to determine whether a 95% confidence interval (95% CI) or analogous measure of precision was provided for time-to-event analyses. RESULTS: A sample of 140 abstracts was reviewed. Of the 65 abstracts with Kaplan-Meier or cumulative incidence analyses, 6 included some measure of precision (6 of 65 = 9%; 95% CI, 2-16). Of the 43 abstracts reporting ratios for time-to-event analyses (eg, hazard ratio, risk ratio), 22 included some measure of precision (22 of 43 = 51%; 95% CI, 36-66). CONCLUSIONS: Measures of precision are not provided in a significant percentage of abstracts selected for oral presentation at the Annual Meeting of ASTRO.