February, 2003
© 2000, 2001 Scott S. Emerson, M.D., Ph.D.
Example: Analyses after 20%, 40%,
60%, 80%, 100% (maintain maximal sample size)
Null: Theta
<= 0 (size = 0.025)
Alt : Theta >= 0.5109
(power = 0.975)
(Emerson & Fleming (1989) symmetric test)
STOPPING BOUNDARIES: Sample Mean scale
a d
Time 1 (N= 69.05) -0.0603 0.5713
Time 2 (N=
138.09) 0.1070 0.4039
Time 3 (N=
207.14) 0.1811 0.3298
Time 4 (N=
276.19) 0.2253 0.2856
Time 5 (N=
345.23) 0.2555 0.2555