Abstract
The principles of the use of statistics in biologic assays are outlined and work sheets are drawn up illustrating the calculations involved in applying the formulae described by Irwin, Supp. J. Roy. Slat. Soc. 4, No. 1, 1937 and Bliss and Marks, Quart. J. Pharm. and Pharmacol. 12, 82 and 182, 1939 to graded response assays.