Bioequivalence and Bioavailability Forum

Imbalanced Xovers: α-inflation? [General Statistics]

posted by Helmut – Vienna, Austria, 2012-12-28 15:37 (4918 d 20:27 ago) – Posting: # 9763
Views: 10,169

Hi ElMaestro,

❝ […] imbalance per se is not causing inflation of alpha in simple crossovers.

Do you know that or do you assume it?

❝ The phenomenon has not been studied or published for 2-stage designs, though.

Yep. Mdme Potvin:

“[…] each stage was assumed to be balanced with respect to sequence.”

Since I want to avoid troubles with regulators

“The imbalanced case is outside the validated framework. The applicant should justify that the consumers’s risk is preserved in the actual study.”

I recommend my clients to randomize the second stage in such a way that imbalance in the first stage is counteracted (e.g., stage 1 TR|RT 10|12, n_total 32, stage 2 TR|RT 6|4).

❝ Did you mean to say something else?

I was just interested in common 2,2,2 cross-overs.

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Complete thread:

Imbalanced Xovers: α-inflation? Helmut 2012-12-27 17:21
- Imbalanced Xovers: α-inflation? ElMaestro 2012-12-28 09:30
  - Imbalanced Xovers: α-inflation?Helmut 2012-12-28 14:37
    - please explain ElMaestro 2012-12-29 08:44
      - I’ll try Helmut 2012-12-29 15:42
- Imbalanced Xovers: α-inflation? d_labes 2012-12-31 13:50
- One Mio sims of 2x2x2 in R in under 1 sec d_labes 2013-01-09 15:23
  - Wow! Helmut 2013-01-09 16:10
    - Unbalanced d_labes 2013-01-09 16:56
      - α-inflation ≈ urban myth Helmut 2013-01-09 18:07
        
        Beer d_labes 2013-01-10 11:07
        
        Beer Helmut 2013-01-10 13:45

Imbalanced Xovers: α-inflation? [General Sta­tis­tics]

Complete thread:

Imbalanced Xovers: α-inflation? [General Statistics]