The proper functions of weibuU, gaussian and logarithmic gaussian distributions were constructed to fit the differences of dose-effect （AE） curves generated by the common four parameters equation of dose-effect curve. Logarithmic gaussian distribution was suitable for fitting the AE appearing as a skew distribution and gaussian distribution was suitable for fitting the AE appearing as a symmetrical distribution. The corresponding concentration of the maximum difference and the standard deviation were indicated. Composite weibull distribution ...
