On the Use of Ranks in Combined Estimates in Quantal Bioassays

If {U_i} i = 1, …, k is a sequence of binary responses of n_i subjects at each of k successive dose levels x_i, there is the problem of the statistical treatment of the observed proportions P_i = U_i/ni when neither the probit nor the logit transformation may be assumed. This paper considers the use of the midranks of the responses for point and interval estimation of relative potency in the case of parallel line assay in particular. More generally the problem of combining the results of several independent estimates using ranks is discussed. Several examples illustrate the method.