Bioequivalence and Bioavailability Forum • 42! SASophylistic power oracle

42! SASophylistic power oracle [🇷 for BE/BA]

posted by d_labes – Berlin, Germany, 2009-09-29 15:37 (5494 d 16:25 ago) – Posting: # 4267
Views: 41,577

Dear guys,

let me take part in your hairsplitting party :-D

.
Hope you have already waited for me.

Here are the results of the SAS Proc Power.
Code can be found here, of course appropriately adapted.

                 The POWER Procedure

        Equivalence Test for Paired Mean Ratio



               Fixed Scenario Elements



       Distribution                   Lognormal

       Method                             Exact

       Lower Equivalence Bound              0.8

       Upper Equivalence Bound             1.25

       Alpha                               0.05

       Geometric Mean Ratio                   1

       Coefficient of Variation           0.075

       Correlation                            0





              Computed Power

                        N

            Index    Pairs    Power



               1        3    0.604

               2        4    0.867

               3        5    0.968

               4        6    0.993

The power is given with 3 decimals only by default. No simple way to change.

Seems the power is calculated in this case totally wrong!
This is astonishing enough, because the same Proc Power code can reproduce most of the sample sizes given in Diletti et.al., at least for power 80%.
Ok, Proc Power is called experimental by SAS, usually means the user shall do the testing and report bugs. Others call such software beta.

My own rolled code (relying on Owen's Q-functions, undocumented but available in SAS) gives:


        Coeff. of

        variation   'true'  lower BE  upper BE        achieved   required

 alpha     (%)      µ(T/R)    bound    bound     N     power      power



  0.05     7.5        1       0.8      1.25      4     0.729014    0.7

  0.05     7.5        1       0.8      1.25      6     0.986992    0.7

  0.05     7.5        1       0.8      1.25      8     0.999577    0.7

—
Regards,

Detlew

Complete thread:

R-Code for Power in 2×2 Cross-over Helmut 2006-12-28 21:33 [🇷 for BE/BA]
- Power in Diletti's sample size table Helmut 2007-01-01 23:59
  - Approximate Power Helmut 2007-01-06 15:17
    - Power Calculation for replicate crossover design mathews 2008-04-03 13:19
      - Power Calculation for replicate crossover design Helmut 2008-04-03 13:49
        
        Power Calculation for replicate crossover design mathews 2008-04-04 13:21
    - Exact Power Helmut 2009-09-25 19:20
      - Exact Power ElMaestro 2009-09-27 23:27
        
        Software validation Helmut 2009-09-28 15:21
        
        All the important answers are here! ElMaestro 2009-09-28 19:12
        
        All the important answers are here! Helmut 2009-09-28 19:52
        
        All the important answers are here! ElMaestro 2009-09-28 20:18
        All the important answers are here! yjlee168 2009-09-28 21:30
        
        All the important answers are here! Helmut 2009-09-28 23:18
        
        42! SASophylistic power oracled_labes 2009-09-29 13:37
        
        Al Gore Rhythms Helmut 2009-09-29 14:52
        
        Al Gore Rhythms ElMaestro 2009-09-29 18:14
        Al Gore Rhythms yjlee168 2009-09-29 23:55
        
        All the important answers are here! yjlee168 2009-09-29 23:49
- R-Code for Power in 2×2 Cross-over KDA 2019-01-23 04:24
  - R-Code for Power in 2×2 Cross-over Ohlbe 2019-01-27 18:24
- R-Code for Power in 2×2 Cross-over Brus 2021-12-02 15:00
  - R-Code for Power in 2×2 Cross-over ElMaestro 2021-12-02 15:15
    - R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 17:30
  - R-Code for Power in 2×2 Cross-over Helmut 2021-12-02 16:57