Bioequivalence and Bioavailability Forum • ABEL ≠ RSABE

ABEL ≠ RSABE [Outliers]

posted by BEQool – 2023-10-09 16:47 (340 d 03:39 ago) – Posting: # 23747
Views: 3,283

Hello!

I have seen this or similar explanation several times:

❝ If you design studies for 80% power and all of your assumptions are exactly realized (T/R-ratio, CV, dropout-rate), one out of five will fail be pure chance. That’s life.

... but I still can't get my head around this.

Lets say I plan study with theta0=0.95, CV=0.20, design="2x2", targetpower=0.8 (all except CV are default settings in PowerTOST), so with sampleN.TOST I get N=20 and power=0.834680

> sampleN.TOST(theta0=0.95, CV=0.20, design="2x2", targetpower=0.8, print=FALSE)

  Design alpha  CV theta0 theta1 theta2 Sample size Achieved power Target power

    2x2  0.05   0.2  0.95    0.8   1.25          20      0.8346802          0.8

If all of my assumptions in a study are exactly realized, doesnt it mean that I would 100% always get bioequivalent formulations (and the study would never fail)?
If all of my assumptions in a study are exactly realized (pe=0.95, CV=0.20, design="2x2", n=20) then I would get the following confidence interval:

> CI.BE(pe=0.95,CV=0.20,n=20)

    lower     upper 

0.8522362 1.0589787

So because a confidence interval is completely within limits 80-125%, my formulations would always be bioequivalent because I would always get this confidence interval with same numbers (CV,n,pe)?

What am I not understanding here?
Thank you and best regards
BEQool

Complete thread:

Outlier in fully replicate BE study Loky do 2021-06-16 00:49 [Outliers]
- Outlier in fully replicate BE study drgunasakaran1 2021-06-16 08:59
  - Widening for clopidogrel BE study Loky do 2021-06-16 15:38
    - Widening for clopidogrel BE study mittyri 2021-06-16 16:04
      - Widening for clopidogrel BE study Loky do 2021-06-16 17:08
        
        Widening for clopidogrel BE study - cherry-picking? mittyri 2021-06-16 17:27
        Widening for clopidogrel BE study drgunasakaran1 2021-06-17 12:01
        Hypotheses Helmut 2021-06-19 12:32
        
        Hypotheses Loky do 2021-07-06 11:51
        
        ABEL ≠ RSABE Helmut 2021-07-06 16:17
        
        ABEL ≠ RSABEBEQool 2023-10-09 14:47
        
        power.TOST.sim and uncertainty mittyri 2023-10-11 12:42
        
        power.TOST.sim and uncertainty BEQool 2023-10-15 11:29
        
        power.TOST.sim and uncertainty mittyri 2023-10-20 21:47
        
        Distribution of PEs Helmut 2023-10-23 10:48
        
        Distribution of PEs BEQool 2023-10-23 19:55
        
        power.TOST.sim code mittyri 2023-10-31 15:40
        
        power.TOST.sim code BEQool 2023-11-02 11:22