1917 Archives of internal medicine (Chicago, Ill. : 1908)  
In connection with a recent study1 of the cutaneous typhoidin test, which was introduced by Gay and Force2 as an index of typhoid immunity, an objective method of reading such cutaneous diagnostic reactions was described. Instead of reporting the test as positive, negative or doubtful, from the general appearance of the inoculated spots, the diameters of the areolae are measured with a suitable millimeter gage, preferably one which can be set to the diameter to be measured without exhibiting
more » ... reading until afterward. The result of a test is recorded as the quotient of the diameter of the test areola divided by that of the control. The advantages of this procedure are, first, that after adjusting the gage to the diameters of the areolae, the bias of the observer can be entirely eliminated in expressing the results of the test, and, second, that the quotients so obtained lend themselves readily to quantitative analyses according to the statistical theory of variables. Reasons were given for using the quotient rather than the difference between the two diameters. It is recognized, of course, that other characters, such as swelling, induration and depth of color, may contribute to the formation of judgments concerning such diagnostic skin reactions. As a rule, however, these characters vary with the diameters ; and for statistical investigations, it is felt that the advantages of the definite and uniform system of measurements possible for the diameters outweigh any objections to the ignoring of other qualities of the reactions. It was found that with the dry preparation of typhoidin used there were average differences between groups of typhoid immunes and nonimmunes, but that the differences were small in comparison with the variation among individuals in the same group, so that the test had little value for the individual case. The desirability, therefore, became apparent of examining possible sources of variability in
doi:10.1001/archinte.1917.00080210104005 fatcat:6hqcoqvqyfgitompoooxzadbd4