February, 2003
© 2000, 2001
Scott S. Emerson, M.D., Ph.D.
Choice of A
parameter
·Lower
absolute values of A makes it harder to stop at early analyses
·Valid
choices of A depend upon choices of P and R
·Useful
ranges for A
-P ³ 0, R ³ 0: 0.2
£ A £ 15
-P £ 0, R = 0: -15
£ A £ -1.25
-
·