Abstract: The invented method is a process to evaluate drug effect in a multiple dose clinical trial. In drug development, finding an optimal dose is normally carried out by a phase II clinical trial. Then a phase III clinical trial will be conducted to demonstrate the selected dose is efficacious and safe. Because the highest observed response rate among the multiple dose groups could overestimate the true response rate of the selected dose, there is difficulty to pool the data from phase II clinical trial with the data from phase III clinical trial for final analysis. As a result, sample size of each dose group in phase II clinical trials is often under-powered to provide sufficient information for choosing an optimal dose. The invented method gives a solution to the overestimation problem. Simulations show that the invented method is better than the existing methods such as Bonferroni's procedure.