Non-inferiority (NI) trials have gained recognition as an effective tool with which to search for substitutes for a standard treatment that is associated with certain undesirable features, such as adverse side-effects, an exorbitant cost, or an extremely complicated therapeutic regimen. Statistical methods have been developed for NI studies with multiple experimental treatments. However, experimental treatments sometimes represent a new treatment with various dose levels, and in such circumstances, identification of the minimum non-inferior dose is a reasonable objective of the trial. Thus, we examine several potential testing procedures with respect to this testing objective. A simulation study is conducted to evaluate their performance, and determination of the sample size is discussed. Two clinical examples are provided to illustrate the proposed method.

非劣效性（NI）试验已被公认为一种有效的工具，可用于寻找与某些不良特征（例如不良副作用，高昂的费用或极其复杂的治疗方案）相关的标准治疗方法。已经为具有多种实验方法的NI研究开发了统计方法。但是，实验治疗有时代表具有不同剂量水平的新治疗，在这种情况下，确定最低非劣效剂量是该试验的合理目标。因此，我们针对该测试目标检查了几种潜在的测试程序。进行了仿真研究以评估其性能，并讨论了样本量的确定。