February, 2003
© 2000, 2001  Scott S. Emerson, M.D., Ph.D.
Session 2: 49
Stopping Rules
Conditions for Early Stopping: Two-sided tests
Test of a two-sided alternative (q+ > q0  > q- )
·Upper Alternative:    H+: q ³ q+         
·Null:                          H0: q = q0
·Lower Alternative:    H -: q £ q-         
Possibilities for early stopping:
·Stop only for the null (when  Tn intermediate)
·Stop only for the alternative (when  Tn small or large)
·Stop either for the null or for the alternative
·