Two-stage sequential tests for proportions and means with follow-up period

AbstractThis paper extends a procedure, based on [1], wherein a sequential probability ration test (SPRT) is combined with a likelihood ratio test that incorporate both sequential observations and additional delayed observations. Two two-sample sequential tests are considered: one for binomial parameters and the other for the means of normal distributions. The essential feature of the method enables us to construct a SPRT with the risk probabilities set greater than the desired level, depending on a number of delayed observations. The terminal decision based on a likelihood ratio test can be made with the desired risk level. The adequacy and advantage of the procedure are discussed and a number of computational formulas is presented to facilitate its applications