February, 2003
© 2000, 2001  Scott S. Emerson, M.D., Ph.D.
Session 2: 39
Inadequacy of Fixed Sample Methods
Critical values depend on spacing of analyses
Level .022 analyses at 10%, 20%, 100% of data
Pattern of                 Proportion Significant
Significance           1st      2nd      3rd      Ever
1st only             .01509                      .01509
1st, 2nd             .00521   .00521             .00521
1st, 3rd             .00068            .00068    .00068
1st, 2nd, 3rd        .00069   .00069   .00069    .00069
2nd only                      .01473             .01473
2nd, 3rd                      .00165   .00165    .00165
3rd only                               .01855    .01855
Any pattern          .02167   .02228   .02157    .05660