Stability criteria for the outcomes of statistical tests to assess drug effectiveness with a single study

At least two adequate and well-controlled clinical studies are usually required to support effectiveness of a certain treatment. In some circumstances, however, a single study providing strong results may be sufficient. Some statistical stability criteria for assessing whether a single study provides very persuasive results are known. A new criterion is introduced, and it is based on the conservative estimation of the reproducibility probability in addition to the possibility of performing statistical tests by referring directly to the reproducibility probability estimate. These stability criteria are compared numerically and conceptually. This work aims to help both regulatory agencies and pharmaceutical companies to decide if the results of a single study may be sufficient to establish effectiveness.