February, 2003
© 2000, 2001  Scott S. Emerson, M.D., Ph.D.
Session 2: 38
Inadequacy of Fixed Sample Methods
Group sequential test: Pocock (1977) level .05
Three equally spaced level .022 analyses
Pattern of                 Proportion Significant
Significance           1st      2nd      3rd      Ever
1st only             .01520                      .01520
1st, 2nd             .00321   .00321             .00321
1st, 3rd             .00113            .00113    .00113
1st, 2nd, 3rd        .00280   .00280   .00280    .00280
2nd only                      .01001             .01001
2nd, 3rd                      .00614   .00614    .00614
3rd only                               .01250    .01250
Any pattern          .02234   .02216   .02257    .05099