Concealed allocation in a research study is the practice of making sure the investigator(s) enrolling patients into a study are not aware of the group to which the patients will be assigned. This video explains how an otherwise “double-blind” study can be conducted without concealing allocation. From the Making Decisions Better: The Information Mastery Curriculum and Assessment Program, an evidence-based medicine teaching program from Clinical Information Sciences, http://ClinicalInformationSciences.com.