1. Symmetric group sequential designs;Emerson;Biometrics,1989
2. Bootstrap tests and confidence intervals for a hazard ratio when the number of observed failures is small, with applications to group sequential survival studies.;Jennison,1992
3. Interim analyses: the repeated confidence interval approach (with discussion).;Jennison;J. Roy. Statist. Soc. B,1989
4. Exact calculations for sequential t, χ2 and F tests;Jennison;Biometrika,1991
5. Group sequential analysis incorporating covariate information;Jennison;J. Amer. Statist. Assoc.,1997