Use of Logarithms to the Base 2 in recording Serological Reactions

The expression of dilution titres for serological reactions frequently requires the use of large numbers. In cases where the antibody content of an immune serum is high, the conventional means of recording the titre may be misleading ; that is, the difference between a titre of 1 : 10,240 and 1 : 20,480 seemingly is greater than that between 1 : 40 and 1 : 80 but both represent only a single dilution step in the usual procedure and have the same degree of precision. Since serological procedures usually involve serial twofold dilutions, the resulting titres are exponential functions of 2. Consequently, we suggest the simple expedient of using logarithms to the base 2 (log 2 ) to express serological titration data.