The Use of the Angular Transformation in Biological Assays

A comparison is made of the use of the angular transformation and the use of the probit transformation in evaluating results from biological assays having percentage responses. It is found that the angular transformation results in making the weights dependent on the number of animals used on each dose and if these are equal the weights are eliminated. The logit transformation is also cited. A two-dose assay design used in conjunction with the angular transformation results in a simplified calculation which can be put in the form of a graph and nomograph for use in the laboratory to estimate both potency and error of the assay as a per cent of the standard. A comparison of the calculation time involved shows that the probit method requires about twelve times as long as the angular transformation method involving graph and nomograph. A comparison of results obtained shows very little difference.