Rapid and accurate determination of the median lethal dose (LD50) and its error with a small computer.

A program for a small digital computer was developed to calculate the median lethal dose (LD50) and its errors. The algorithm employed in the program was based on a method described by Bliss. Modifications introduced by Finney are also discussed. The results indicate a high degree of accuracy compared with calculations performed by Bliss. The accuracy and speed of calculation exceeded those possible with simplified and graphic methods. The data and results for four toxic compounds are presented.