<prompt> Randomization meansMixing of cases and controlsSelecting casesSelecting controlsVaccine and Erythromycin  <response>: Randomization is a statistical procedure by which the study paicipants are allocated into groups usually called study and control groups; to receive or not receive an experimental preventive or therapeutic procedure, maneuver or intervention Ref: 25th edition, Parks Textbook of Preventive and Social Medicine, Page no. 90 