A note on Harold S. Diehl, randomization, and clinical trials

Harold S. Diehl and coworkers published results from a remarkable trial on the efficacy of vaccines for the common cold in 1938. The original report states that patients were assigned to treatment and control groups "at random." Diehl's study has been referred to as one of the first instances of a randomized, double-blind, placebo-controlled trial. No description of a formal randomization scheme is given in the 1938 report and an unpublished paper of Diehl's suggests the use of alternate assignment in the study.