Bioequivalence and Bioavailability Forum • “Group-by-Treatment Interaction”

“Group-by-Treatment Interaction” [Design Issues]

posted by Helmut – Vienna, Austria, 2024-10-22 14:47 (170 d 09:59 ago) – Posting: # 24244
Views: 3,810

Hi BEQool,

❝ ❝ ❝ Here agency is asking for the BE of any one of the group, if group-by-treatment interaction is significant (p<0.05).

❝ ❝ 0.1 not 0.05. BTW, did you bother reading the presentation I linked in my OP?

❝

❝ Why would the alpha for G*T interaction be 0.1 and not 0.05 like almost always?

The original post is five years old… At the time being 0.05 indeed. The 0.1 was used by the FDA in analogy of Grizzle’s dreadful test¹ for unequal carryover.

“… a preliminary test should be made at some high level of significance, say α = .10 or α = .15”

It is evident that increasing the level of any test to offset inadequate power leads to an increased false positive rate.
BTW, the FDA’s 2022 guidance² does not specify a particular level but has Grizzle in the references. Even worse, Alosh³ as well:

“To improve the power when testing for an interaction, some suggest using a test size of 0.10 or in extreme cases 0.20, particularly when there is reason to suspect a specific interaction exists. While an increase in the test size makes it easier to detect an interaction, this would be at the expense of an increase in the chance of false positive findings. The choice of the test size can depend on the context and it would be inappropriate to say a specific test size is applicable in all scenarios.”

Make your pick.

Grizzle JE. The Two-Period Change-Over Design and Its Use in Clinical Trials. Biometrics. 1965; 21(2): 467–80. doi:10.2307/2528104.
FDA (CDER). Statistical Approaches to Establishing Bioequivalence. Guidance for Industry. Draft. Silver Spring, MD. December 2022. Download.
Alosh M, Fritsch K, Huque M, Mahjoob K, Pennello G, Rothmann M, Russek-Cohen E, Smith F, Wilson S, Yue L. Statistical Considerations on Subgroup Analysis in Clinical Trials. Stat Biopharm Res. 2015; 7(4): 286–304. doi:10.1080/19466315.2015.1077726.

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

Possible reasons for group effect GM 2019-07-20 07:36 [Design Issues]
- Group “effect” Helmut 2019-07-20 14:02
- Possible reasons for group effect ElMaestro 2019-07-20 19:20
  - Possible reasons for group effect GM 2019-07-23 06:23
    - “Group-by-Treatment Interaction” Helmut 2019-07-23 10:32
      - “Group-by-Treatment Interaction” BEQool 2024-10-22 12:39
        
        “Group-by-Treatment Interaction”Helmut 2024-10-22 12:47
        
        OT: A choice between mittyri 2024-10-22 16:03
        
        OT: A choice between BEQool 2024-10-23 11:02
        
        OT: A choice between Helmut 2024-10-23 11:58
        
        OT: A choice between BEQool 2024-10-23 13:17
        
        OT: A choice between Helmut 2024-10-23 13:22
        Groups: Overlapping CIs Helmut 2024-11-03 11:36
        
        Groups: Overlapping CIs BEQool 2024-11-05 09:14
        
        Groups: Overlapping CIs Helmut 2024-11-05 10:12
        
        Groups: Overlapping CIs BEQool 2024-11-06 07:44
        
        Groups: (Hardly‽) overlapping CIs Helmut 2024-11-21 13:20
        
        Groups: (Hardly‽) overlapping CIs BEQool 2024-11-22 12:32
        
        Groups: (Hardly‽) overlapping CIs Helmut 2024-11-22 12:58
        Multiplicity? Helmut 2024-11-23 13:05
        
        Groups BEQool 2024-11-26 08:15