February, 2003
© 2000, 2001, 2003 Scott S. Emerson, M.D., Ph.D.
Session 1- Overview: 50
Statistical Issues
In monitoring a study, ethical considerations may demand that a study be stopped early.
The conditions under which a study might be stopped early constitutes a stopping rule
·At each analysis, the values that would cause a study to stop early are specified
·
The stopping boundaries might vary across analyses due to the imprecision of estimates
·At earlier analyses, estimates are based on smaller sample sizes and are thus less precise