February, 2003
© 2000, 2001, 2003 Scott S. Emerson, M.D., Ph.D.
Session 1- Fixed Sample Design: 77
Criteria for sample size (cont.)
Sometimes constrained by practical limitations
·Compute alternatives that can be discriminated from the null
-Frequentist: alternative for which study has desired power
-Bayesian: alternative for which posterior probability is sufficiently high when null posterior probability is low
·Determine power (frequentist) or posterior probability (Bayesian) criterion which corresponds to a particular alternative
Determining the Sample Size