Bioequivalence and Bioavailability Forum • Banana splits

Banana splits [Two-Stage / GS Designs]

posted by Helmut – Vienna, Austria, 2015-06-02 02:48 (3582 d 14:25 ago) – Posting: # 14889
Views: 20,270

Hi Dan,

plots from my garbage-collection about asymmetric splits of α_adj. GMR 0.95, target power 80%. Stage 1 sample sizes 12–72 and CVs 10–80%; both assessed with a step size of two. 10⁶ sim’s for the Type I Error and 10⁵ for power.

Left panels: TIE
Contour lines at 0.0025. Thick lines enclose the area of significant inflation of the TIE (i.e., >0.05036). Yellow circle location of TIE_max. Gray plane at nominal (target) α 0.05.
Right panels: Power
Lower surface stage 1 and upper surface in the final stage. Contour lines and gray plane at target power 80%.

Haybittle/Peto: misused 0.001/0.049 (CIs 99.80/90.20%)
TIE_max 0.0585 (at n₁ 12, CV 24%)

Haybittle/Peto: adjusted 0.001/0.0413 (CIs 99.80/91.74%)
TIE_max 0.0499 (at n₁ 12, CV 22%)

O’Brien/Fleming: misused 0.005/0.048 (CIs 99.00/90.40%)
TIE_max 0.0570 (at n₁ 12, CV 24%)

O’Brien/Fleming: adjusted 0.005/0.0416 (CIs 99.00/91.68%)
TIE_max 0.0501 (at n₁ 12, CV 24%)

Zheng et al.: 0.01/0.04 (CIs 98.00/92.00%)
TIE_max 0.0488 (at n₁ 12, CV 24%)

Zheng et al.: adjusted 0.01/0.0412 (CIs 98.00/91.76%)
TIE_max 0.0498 (at n₁ 12, CV 26%)

With Haybittle/Peto the TIE may hit all over the place; O’Brien/Fleming performs slightly better. Zheng et al. is overly conservative.
Note that these adjustments are applicable to a GMR of 0.95 and target power of 80% only. More deviation of the GMR from unity and/or higher target power generally requires more adjustment (i.e., lower α₂ ⇒ wider CI). I know some people using HP for a GMR of 0.90. :no:

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Complete thread:

Does unequal alpha distribution make sense? Dr_Dan 2015-05-19 08:29 [Two-Stage / GS Designs]
- Maybe; but watch the TIE! Helmut 2015-05-28 15:04
  - Advantages d_labes 2015-06-05 09:35
    - Advantages ElMaestro 2015-06-05 10:07
      - Advantages – performance measure d_labes 2015-06-05 11:21
        
        Advantages – performance measure Helmut 2015-06-05 13:29
        
        Advantages – performance measure d_labes 2015-06-05 21:27
        
        Advantages – performance measure Helmut 2015-06-05 23:29
        
        Histogram wonder d_labes 2015-06-06 12:58
        
        Histogram charlatanry Helmut 2015-06-09 13:43
        
        Histogram beauty d_labes 2015-06-09 14:55
        
        Histogram beast Helmut 2015-06-09 15:24
- Does unequal alpha distribution make sense? Dr_Dan 2015-05-29 08:33
  - Does unequal alpha distribution make sense? ElMaestro 2015-05-29 09:31
    - Does unequal alpha distribution make sense? nobody 2015-05-29 12:56
      - Old beliefs die hard Helmut 2015-05-29 13:27
        
        Old beliefs die hard nobody 2015-05-29 13:41
        
        Old beliefs die hard Helmut 2015-05-29 18:08
        
        Old beliefs die hard ElMaestro 2015-05-29 18:57
        
        Old beliefs die hard nobody 2015-05-29 20:06
        ♩ ♪♫♬`·.¸¸.·´`·.¸¸. Helmut 2015-06-02 01:52
        
        TSD only an option in exceptional cases Dr_Dan 2015-06-02 08:00
        
        TSD only an option in exceptional cases nobody 2015-06-02 09:23
        
        OT Helmut 2015-06-02 12:07
        
        OT nobody 2015-06-02 12:41
- Banana splitsHelmut 2015-06-02 00:48