ON THE CORRELATION-COEFFICIENT BETWEEN THE TD50 AND THE MTD

The existence of correlation between the carcinogenic potency and the maximum tolerated dose has been the subject of many investigations in recent years. Several attempts have been made to quantify this correla tion in different bioassay experiments. By using some distributional a ssumptions, Krewski et al.((1)) derive an analytic expression for the coefficient of correlation between the carcinogenic potency TD,, and t he maximum tolerated dose. Here, we discuss the deviation that may res ult in using their analytical expression. By taking a more general app roach we derive an expression for the correlation coefficient which in cludes the result of Krewski et al.((1)) as a special case, and show t hat their expression may overestimate the correlation in some instance s and yet underestimate the correlation in other instances. The propos ed method is illustrated by application to a real dataset.