February, 2003
© 2000, 2001 Scott S. Emerson, M.D., Ph.D.
Session 3: 37
Boundary Scales
Example: Constrained O’Brien-Fleming boundaries on fixed sample P value scale
Null: Theta <= 0      (size  = 0.025)
Alt : Theta >= 0.5    (power = 0.975)
(Emerson & Fleming (1989) symmetric test)
STOPPING BOUNDARIES: Fixed Sample P-value scale
                            a      d
    Time 1 (N=  64.31) 0.9773 0.0005
    Time 2 (N= 128.61) 0.4989 0.0023
    Time 3 (N= 192.92) 0.1231 0.0102
    Time 4 (N= 257.23) 0.0224 0.0224